I found this as I'm thinking of an electric tandem... Or at least adapting a 'unique' tandem I have to make it electic. Maybe you all can help me - but realize I'm a complete novice and not matter what I do, I'd have to pay someone to make any adaptations.
I have a son with high functioning autism. He pretty much can do anything, but it takes longer and is "looser" with low muscle tone. He just turned 12 and is tall and fit (dances and walks a lot) but we haven't gotten him to bike riding yet. I think he'll get it this summer. He has the balance part down, but the pedaling, while steering, while balancing... that has been tricky (but we also haven't worked on it much).
But even if/when he gets to biking, it's going to take awhile for him to get the stamina/strength to go up hills due to low muscle tone. We have a tandem of sorts, bit it's a bit unusual. We've used it some, but it's so heavy and it's been basically ME providing all the push/pull power and even at my top fitness 5 years ago (now I've gone all soft again - but working on it) I couldn't keep up with my husband. I would have to get off and walk at any hill.
Here is the bike we have: (Link Removed - No Longer Exists)
We got it used... its' their basic model. They now have bigger ones. Maybe that might be better - or another electric tandem.
Anyway... I'm 5'6". My 12 year old is already 5'9". He'll probably get to 6'3/6'4" based on his growth trajectory compared to his older brother's who is 6'2". This buddy bike is probably already too small for us with him as the front rider. I cannot have him be the back rider as that is who does the controlling. BUT... perhaps it could be converted to electric? Or we could get the bigger version to be electrified (Link Removed - No Longer Exists)
The down side to this is that the pedals will keep moving for the front rider even though they may be "resting" and that can be problematic if he's not wearing/using toe clips...So the comment above captain and stoker being able to pedal or coast is important.
I think this would help my son learn to ride and be less frustrating. As we home school now too, it's something he, I, and my husband could do together. Heck even my husband and I could bike together on an electric tandem too.