You should be ok as long as its not built lik an old landrover where each pannel bolts to the chassis or bulkhead, most modern cars are a pre fabricated body and mounted on to the chassis. Have a look underneath there will be about 8 body mounts 4 each side along the chassis, I wont go into all the details involed like extending brake lines etc, as you have a firm doing the work.

www.centraloffroadclub.co.uk for free fun offroading in the midlands