Allrighty, time to post an update...the panels and parts arrived yesterday and today I spoke with Jimmy Davis at TM about mounting and with a local adhesives expert about adhesives.
First the panels...the 120watt panel is 26"X58" which is pretty darn big when you actually have it in your hands! The 50 watt is a much more manageable 26"X26". Although kinda unwieldy, the weights are quite reasonable...the big one is about 25 lb, the smaller around 11 lbs. They come with just a connection box on the back (no wires attached) so I haven't yet had a chance to hook them up to the charge controller and a battery and put them in the sun for some testing (will do that on Sunday after I get a couple of hot deadlines met). I can say that the folks at RV Solar did a really good job of packaging them for shipment....lots of sturdy spacers and tape and double boxing.
Jimmy Davis was right up front about Solar on TMs...the factory doesn't do this so he doesn't have much knowledge on the subject or recommendations on best practices. He did, however, say that it really doesn't matter where the panels are mounted on the roof (center or edge) because the total weight is relatively low (only about 36 lbs) and that any side-to-side weight imbalance can easily be handled by tweaking the torson adjustments (especially since I have the heavy duty torsion bars but don't have the roof air).
He also said that there are actually two square aluminum tubes at the top corners of the roof in the newer TMs...one in the edge of the roof section and one in the top of the wall section...and these are stacked vertically (roof over wall). Thus, if I wanted to mount the panels on the edge of the roof, I'll be able to sink longer screws down through two structural elements.
I asked if there might be a problem with glued-on panel mounts causing the TM's skin to delaminate from the foam core and he said he'd never heard of that happening to anyone.
Finally, he said the soft rubber strip on the top edges is basically cosmetic only...it hides the screws that actually attach the roof to the wall...and can be cut away as needed to mount the solar panel z-brackets. Oh...and they use a regular clear silcone caulk on their screws to keep the water out.
Finally, had a great discussion with a sales rep at a local branch of the Fastenal Corp (
http://www.fastenal.com) (these guys are the experts in fastening things together!) and after I explained my requirements he said he'd do some research and get back to me. Welll...after he talked to a Loctite tech rep, it turns out they recommend the same adhesive I thought would be best:
Loctite Depend (
http://www.loctite.com/datasheets/tds/Product_330.pdf). They don't have it in stock but will have it by Monday. About $32 for a kit with 25 ml of adhesive (and tiny spray can of activator)...a few bucks more than the cheapest on-line price but I also don't have to pay shipping.
Soooo...the plan now is to mount the panels along the curb (door) side top edge right next to the awning. I'll use sheet metal screws to attach the Z-mounts to the underlying tubing on that side of the panels. And on the other side of the panels I'll rivet 5"X5" aluminum plates (1/8 inch or thicker) to the Z-mounts and bond the plates to the top of the TM with the Depend adhesive.
Before final mounting there'll be some testing and torsion tweaking with the panels affixed with duct tape.