My wheelchair bound son somehow manages to out drive the components on this rig in just a few weeks???

It appeares that one of the bolts on the rear drivers side trailing arm broke and then the arm tore off of the bushing mount on the other side?

Anyone have a Drivers side rear trailing arm for sale of know of anyone that can make me a new one or a set of upgraded ones?
It is very important to get this thing up and running ASAP it is the only thing that makes him happy and feel normal! We just moved him off his quad because he just wasn't strong enough to ride safely anymore and now he is real sad that this broke so soon!

Also with his disability (muscular dystrophy) I was looking for a way to put power steering on it for him. I saw the electric bbut was wanting to do a real hydro setup I think. I want to make this thing as easy as possible for him to operate.
Thanks Phil