Landyacht for paraplegics?? Blokart have already done it and for two people.
Quadraplegics? They will have to be passengers with a paraplegic pilot.
Ask the bloke here:-
http://www.blokart.com/#MapFrame or better still here:-
www.blokart.com.au/I am sure he will have all the answers to your questions and be more than willing help you to the utmost of his ability.
Seems that a Goole search or any other internet search on landyachting pops this forum up. Maybe it is the rite site.
Dig deep enough here and you will find the gold.
Speaking of rites, I have heard there is a particular cult of Land Sailors that participte in a nite rite of a particularly hedonistic nature only open to graduates of LLFUOLS (Le Fools). Beware of cults. They are dangerous.
So, as I was saying, all the information you need is on this site if you are willing to dig for it.
I have given you two directions in which to look but I am not going to do your work for you.
Why are all these university lecturers choosing "land sailing for the disabled" as an assignment topic??
Why can't they pick something more practical like "build a better mouse trap"?