Which adhesive caulk for solar panel mounts??

Wanted to say thanks to all those that responded to the original post. While I was waiting on responses to the original post, I also emailed Winnebago with pretty much the same request. Within 24 hours my response from Winnebago was as follows; "You can use both. The adhesives we use are the 3M style glues and the screws are self-taping no longer than 1 inch. The attachment shows the roof prints to help you find the cross members to screw into." I also received four pdf files outlining the roof layout on the 2008 Access. Very impressive response with a very quick response.