I had a dog who should have had SA, among other things. She had been abandoned, nearly starved to death, had lost her hair, and had been shot to boot. She was, however, bombproof (and I mean bombproof) when it came to people. She had other issues that worsened when she became my grand "old lady houndie." One of them was ripping up the comforter or blanket on my bed when I left her (to go to work, run errands, etc). I think now that she DID have some SA issues. She also became on-leash dog aggressive. She had been attacked by the neighbor's Golden a few times (weird but true) when she was tied up outside.
Background: When I first got her, my landlord freaked out and told me I had to take her back to the pound. And I turned on the waterworks, but I meant them. I told him no way could I do that to her. The first night I brought her home, I gently bathed her, fed her, and then she slept, hard, for about 12 hours. No way could I take her back. So, he said I had to leave her out during the days (when I was at work--just out of college, got a managerial job about 100 miles away, so I moved there, rented out a farmhouse, and acquired that hound). She learned how to get out of the dog run (surprise surprise) that he kept there, and I bought her a dog house and tied her up. And that's where she was attacked. After my landlord got to know her, and see that she was learning some manners, he said she could stay inside and things went on from there.
We were kicked out of the training class, but it was a Scotch Pines class and looking back now, I'm so glad. (Her barking was impossible, they said--which, duh, was why I wanted in to begin with.) I bought some dog training book and went from there. It was Koehler-based and that's how she learned. When we'd walk and she wouldn't loose-leash it, I'd pop her. When she didn't sit when asked, I'd pop her. When she didn't come when called, I'd go and get her and pop her all the way to where I wanted her. When she wouodn't stay on command, I'd take her back to the spot, say "No" as sharply as I could, and then make her do it again. When I wanted her to be quiet, I'd squeeze her mouth shut and say "quiet" until she she was. When I was tired of her snooping on walks, I popped her until her nose came up while saying, "Keep your nose up." When I wanted her to retrieve, I pinched her ear while I shoved the ball in her mouth.
My point is that this took years for total reliability and that only happened in certain instances. She always wore a "training" collar of some type. I'd have a buckle on on her (for looks) and then I'd have her training collar on her. It took me years to teach her to be quiet with a hand signal that mimicked what I did to her muzzle. It took me years to and lots of reminders/pops to teach her to sit and stay. She learned to loose leash it when we walked, and she loose-leashed walked when other people took her walking, too. She learned to be quiet on a hand signal. But not when she was in the very back of the car, kitty corner to me, where she knew she was "safe" because I wouldn't/couldn't follow through.
When I look back on our relationship now do I wish I'd tried more of what you're trying with Marvin? Yes. Absolutely. When I loosened up some with my hound, and I said, "Let's go find it," she was thrilled. She was right there with me. She was my best buddy who would wander around with me hours afterward. Had I been a better dog owner to my hound, I would have done what Houndlove has been doing. Only later, after going through situations with these two terriers I have now, have I been able to really reflect on what I did right AND wrong with my hound. I wish, now, that I focused more on "what to do" instead of on "what not to do." By that I mean, Don't pull, don't stand up, don't walk off, don't ignore my recall command--things like that. I wish I had been able to build a better, tighter, relationship between us so that she would have run straight to me when I called, would have sat with a smile when asked to, etc. But, my focus was on the "don't do" things and not the opposite.
That said, I do say things to my dogs now. No popping, no body blocks, none of that--but I say, "eh eh" (annoying sound) when they're about to head into somebody's yard. With my hound, I anticipated and I got ready for a pop; with my terriers, I anticipate and I either change the subject (I say "Let's go") or I say "eh eh" (if I'm too late for the other timing-wise). I no longer touch my dogs physically except for loving pats, strokes, etc. No more. No more "training" collars. No more muzzle holds, no more leash pops. No more yanking and popping if they've broken a loose-leash walk. Period. I have been known to take one treat outside and then call them and the first one to me gets it and the other gets nada. I have done that. So yes, I do some "mild aversives," if you can call what I'm currently doing that. I have said, "Out" when I catch them in my garden beds. I have said "Out" when my male puts his whole head in the fridge. What would a

ostive-only trainer say? She'd say that I need to focus on giving him something to do when I go the fridge (like "sit on your rug" or something), but we're all human and we all get busy, and I'm not a perfect handler.
I'm getting better and my dogs have really bought into what I'm doing. I wish I had been this way with my hound.
BTW, should you compromise? Absolutely not. Can Marvin handle a "eh eh" from you or an "Out" or a "Leave it" when he needs it? Only you know how that would affect him. My female can be more affected by an "aversive" than my male and so I have to work harder to be more proactive with her than my male. I can say "Out" to him and he backs out where she stands there, super still, flicking her ears around, seemingly trying to take it all in. Does that make sense?
Edited to add that I wish I would have done some counter conditioning with her leash aggression, too. I managed it and made sure she was safe but I never made sure that she
felt safe by working to eliminate the fear she had when she was on leash and around dogs.