Hi,
First of all, your attached photo is really cute, and a perfect one for the open eyes you talked about when he wakes early from his naps!
I know it's frustrating - I've been there. It sounds like you have done a really good job trying out different things. I never had too much luck with holding through the jolts either, it worked occasionally, but mostly my lo woke up. I didn't answer your post because I am an expert by any means, but because I could sense the same desperation I have felt at times.
I thought I could throw out a few other suggestions, that may or may not work with your lo, but here are they are anyway: at 11 weeks my lo responded well to shush/pat in the crib while on her side. She learned to get comfy on her side and that helped her sleep through the jolt sometimes because she had pressure on one whole side of her body. I would watch her as she jolted, and her arm that wasn't underneath her would flail, but then because the rest of her body was still, she made it through. I used a sleep positioner to keep her on her side, as I knew she liked it. ---oh, I just read that you swaddle - that should provide the pressure anyhow. Unless he needs a tighter swaddle, like the ones that velcro or something?
You mentioned that you didn't think you were stimulating him enough? I would play with that a little. In my case I found that I was actually overstimulating my lo, and that's when the toughest bout of short naps plagued us. She tolerated all the activity really well, and acted happy, but she just couldn't turn it off when it was time to sleep, and it caused her to wake easily. So I would try stimulating even less first, and if that doesn't help, you could try more. (But always start the A period with the most stimulating activity and then work your way down to the most mellow as it gets closer to nap time). At that age, it doesn't take that much to get pretty wired and tired.
I understand it is difficult to have your training interrupted with inconsistency with another parent. Can you get him on board somehow? If it helps, my husband thought it was all a little too complicated at first and thought I was making a mountain out of a mole hill. But when our lo started falling asleep on her own, and staying asleep, he was basically kissing the ground I walked on, and was really grateful I was dedicated to the cause.
Anyway, whatever you do, don't be too hard on yourself. You can try some other things, and I'm sure you'll get more suggestions from the "experts" out there. It will get better. Although it may take more time than we want it to!
Good luck,
katemom