The fiberglass raised roof might not have the structure to support a standard roof rack, even if you could clamber up and down reasonably.
I think your friends concerns are probably unfoudned in your case. I also suspect it would be pretty obvious when driving if the cargo carrier started doing inappropriate things, assuming you can see it at all...and quite possibly even if you can't. My concerns would be a little more basic: are the lights obscured? is the radiator airflow impeded to any great extent? is the cargo secured sufficiently well so it won't suddenly come loose and bonk the windshield? does it overload the front axle overloaded (pretty unlikely here, I think)? And those questions are fairly easily answered, too.
As for someone to check it out, one option may be to look up a truck chassis/frame/spring shop. If you were around me I'd suggest Bailey Spring and Chassis, but they're a pretty long drive from southern New Hampshire and I'm sure there are a fair few decent ones that are closer.
