I've used something like that on my old '72 Ford Bronco. Home made and worked well, however, I did tie the kayaks to the front bumper, as well as the gutter tie downs that I made.
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For the pop-up truck camper, I use this bracket that I bolted through the "C" channel that goes around the cab-over section of the front of my All Terrain Camper Bobcat. Very sturdy. FWC's are built the same.
I just leave the kayaks attached to the tie down strap and remove the tie down strap from the bracket to raise the roof. I do have the gas shock lifters and often use the crank up speaker stand to raise the roof with up to 4 kayaks on the roof.
I do have the Yakama track and the two Thule racks that I use to tie down the other areas of the kayaks with nothing holding the rear of the kayaks. I've probably done about 40,000 miles this way on various pavements at slightly lower than freeway speeds and lots and lots of dirt roads of various conditions. I usually drive slow, I'm in no hurry, ever.
One bracket in the front would work. And, you may think about using two of them on each side of the camper, for a total of five brackets.
I had to buy 10 of these brackets and I think I have maybe half of them left in the garage after selling a couple to other WTW forum members. It may take a little time to locate them as the garage is in a state of disarray thanks to a recently evicted brother-in-law.
They were $5 each, and I can probably ship up to 5 of them for another $7.
If you want any, just let me know how many.
Unless you're in a hurry, I prefer to receive a check or postal money order in the mail.
We can do the address exchange via a Private Message.
Or, see what you can find on the internet that might do the same type of job.