Hey there all. I'm new here. I don't yet have 3 wheels, but am shopping for a new bike. (Current ride is a Triumph Sprint RS). I need some advice on accessibility modifications.

My 16 year old son has Duchenne Muscular Dystrophy. He's been riding behind my on my Triumph for over 10 years using a special harness and belt that attaches him securely to me. Unfortunately, as time goes by he's losing the core strength to continue to do this safely. So I'm exploring options.

Here are the challenges that I need to overcome to keep him riding.

1) Seat height - He's now over 100lbs so lifting him up on the back seat is getting challenging. His legs are too weak to help, so it takes on person to lift him, and a second person to lift his legs over one side of the seat or the other.
2) Balance - his core muscles are able to hold him upright, but during anything but gentle acceleration I worry about him leaning back further than his body can correct for. Braking is ok, but evasive turns aren't going to be possible for long.

Things I've thought about doing:
- trade my bike in for a touring bike (ie: GoldWing) - You have to work really hard to fall out of that passenger seat. It's also really expensive, and makes lifting him in harder yet.
- Can Am Spyder - Again expensive. I took my son to the local dealer, and it was very hard to lift him into the back seat. It's pretty high up, and you can't really get really close.
- Can Am Ryker - Less expensive, and easier access to passenger seat. I tried him in that with the fold down backrest. I'm thinking that a transfer belt around him and the backrest could hold him from sliding side to side.

If I went with the Ryker - then for the longer term I'm wondering about making a passenger seat for him out of something like a Kart racing seat. Then I could maybe put a 5 point harness on it so he doesn't go flying when the pace picks up.

Here's a photo of me loading him currently https://theresawiebephotography.pixi...jE1NzA0MDE2OQ/

Anybody have any ideas I've missed?