Attaching Roof Rack on Wind Up Camper

Might be worth while reconsidering the idea as the winding mechanism isn't designed to lift anything but the actual camper top.
If you break the cables they are a PITA to fix.
We had a windsor camper years ago that had two bars on it, large stickers on both sides and near the winder handle to not exceed so many kgs (way less then 100kg's from memory) and to unload it before raising the top.
The winding mechanism (cables and pulleys etc) are not designed to handle anything more than the actual camper top and even when it is down the weight all goes back onto the rubber seal between top and bottom.
The dealer we bought ours from suggested that the racks be used for nothing more than surfboards or a light canoe, definately not a boat or the like.
FWIW our racks were bolted through, a piece of angle sat on the outer edge with two bolts going down through the roof and frame, lots of silicone to seal it. To access the nuts you had to remove the side lining on the inside.

Hi - if you look at latest from jayco they actually will sell you a rack to fit campers for a few hundred bucks. they had a long waiting list though as they were quite popular. they say to keep load under 130kgs (but their personal recommendation to me was under 100kgs) and definately unloaded before winding up roof. i fitted one of my own to my last camper and included a basket on the racks. firstly it was too heavy and we had to modify it, then it worked just fine. the jaycos have a brake system on the winder so the load works ok. i also made and fit steel angle supports that slide in under the roof and sit on the lower body sill to take the extra weight. it is actually recommended to use these anyway with or without a rack in the different camper repair manuals. they can be steel or even timber and whenusing them back the winder off a touch and they do all the work, not the winch system.

the roof racks normally have steel angle feet at the base that sits on your roof. these should be fixed thru the side NOT the top and then you will minimise any possibility of future leaks. When tek screwing fill hole with sealant first and use two screws per foot. screws only need to be about 25mm long or they will pierce right thru the sides. the steel angle for these feet only have to be about 30 x 30mm in size (just check first what will fit on your camper) and then will normally fit above the sail tracks for annexes etc. From memory I used steel around 32/35mm square for my uprights and rails. just be aware that if you overload them they will bow. if you can weld your half way there.

most camper/van manufacturers wont recommend any accessories like racks on roofs or even on the rear for bikes or boat motors, even on the A frames. but if you look around you will find plenty that built correctly have proven to be successful. good luck with it