Locate a place that handles paint and auto body repair suppliess for auto body shops. They should have an assortment of adhesives from common RTV to the stuff used to 'glue' body parts together. You should be able to find what you need there. I have used an adhesive called Siliprene (sp) but it got rock hard when cured and required heat to soften it if you had to seperate ehat you 'glued' together.
'07 Winnebago Journey 34H, ISB-02, MH2500
Toad - '08 Ford Taurus X
Blue Ox, Aventa
US Gear UBS