i have always been interested in having a roof rack on top of my blazer but was worried if the fiberglass could handle the weight of whatever's on there. but last week i bumped into a fellow k5 owner in a parking lot who had an aftermaket roof rack on with a spare and a hi-lift mounted...the exact setup i wanted. he has had no problems and gave me some tips on installing it. so yesterday i went and ordered mine. basically how much can i put up there without worrying about cracking the top? for example could i put two 35" spares up there???