Did not do SB camper in LB truck, but did go with Torklift. the company is great to work with, answers all questions quickly. They will adapt to your current situation with a segment of chain, mine came with about 18 inches plus a D ring on each.
When you get a longbed camper you will be ready to go. Would go with the fastguns if in budget, nice and quick adjustment when camper is not installed on truck exactly the same.
Know you don't want COG input so none offered. Do check the rear axle loading, it may be larger than you expect.