I agree on all your remarks Rosco.
Especially about drilling in the FRP-top. I did it that way as well. The wall thickness is minimal. Most of the sides are double walled and that complicates the matter.
Then, the FRP is not up to the forces that act on it. I took the rack off the moment I discovered that cracks were developing in the topcorners of the backdoor openings.
All I used to have on there was I kind of integrated Aluminum fuel tank of about 50 liters. The roofrack/fueltank was bolted to the FRP-top and had large "flaps" that formed the studs on the roof so as to spread the weight.
I now have a completely different setup. See photos below.
The rear attachpoints have backing plates in the same shape. This way the stress is spread over a large area.
It has been on there for more than 35.000 km now, 15000 on a trip to Kazakhstan under very poor conditions and two desert trips totalling about 12000 kms.
During my last trip I had an accident (nose dived into a ditch), strapped gear in the back flew around, my glasses ended upon the dash-board! The roofrack still in place, no damage. I have to admit the roofrack was unloaded (just the antennas) but I've seen roofracks completely thrown of a rig under similar conditions.