Most of the peel and stick alumium roofing products I have seen (and I am a profesional roofer) are nothing more than a very thin (6-10mils at best) aluminum foil over some type of adhesive or modifed base sheet. For quickie repairs on my Airstream I use the aluminum foil tape, it works great on seams, missing rivets or to plug a hole where I removed something like a dead bolt lock or cable entry cap. I seriously doubt that any peel n stick products would work as a replacement for a structural panel and yes the interior panels are considered part of the structure. As far as using it on the interior to stop leaks, you are going to be better off stopping the water at the point of entry. Patching from the inside will still allow the water entry into the seam and eventually it will find somewhere else to come inside around the patch. For a temporary solution it would probably work fine.