Loading is no problem as I always unhook the fuel line & run the gas out of the motor anyway.
run the fuel out, then winch the boat all the way up & pull on out.
Curt I wondered about that myself but honestly I wasn't worried about the bottom of my ol stump jumper. I WOULDNT consider roller bunks for a glass boat or maybe even a high-perf tin boat like an Xpress but for a plain ol beater they're fine. My bunks are 8ft long instead of the usually shorter bunks with mini-bunks or a roller under the bow so the weight is spread over a longer area of the bottom.
Very interesting. Made me wonder if a heavy boat might roll sightly back and forth when the tow vehicle stops and starts. Possible excess wear and strain on the winch and tie downs?
I was looking at these same roller bunks about 4-5 years ago.....Xpress/Backtrack trailers recommend NOT to use them on their hulls due to the weight spotted on such small areas on the Alum.