Well seeing as most all 1/10 scale onroad bodies are about 200 mm wide, I am thinking one would have to narrow up the arms and suspension bits to fit underneath the onroad shell, I would be interested to see what you may come up with.....
says right here the XS is 280 mm wide 360mm long so if looking for onroad shells, I would have to say maybe look for 1/8 scale onroad shells as they would probably be easier to adapt to something like you are thinking....
Keep in mind also that most 1/10 scale onroad wheels are 2.0 wheels and not near as wide and the next thing to consider is the gearing of said vehicle....
If ya just wanna stick on an onroad shell using the basic xs I am sure there are several which will do just that, if what you are proposing is to make a scale looking vehicle I think ya probably going to have to look elsewhere....