Side mirror adhesive
 

Hello everybody and thanks in advance for any input.
My driverside door mirror glass has become detached from its plastic (?composite) backing plate inside the housing. I want like to reattach it, but was concerned about 1) which adhesive and prep for a lasting bond, and 2) since the mirror is heated and the old adhesive seems to have been a very thin continuous sheet, presumedly to maintain even thermal conductivity so the mirror defroster will work evenly, how do I best obtain this uniform coating?
It seems that regular mirror adhesive would be too strong, too fast setting, would require several packs to cover the whole back of the mirror / backing plate, and likely would pool into a mess if several cc's were applied to the vertical surface. And the backing plate has a couple of tiny ripples in its smooth surface, so at least a tiny amount of thickness of the adhesive will be necessary to get uniform adhesion & heat conductivity.

I am sure I can "wing" this very minor repair, just wondering if there is a "right" way to do it.

I’ve got an extra mirror (glass only) you can have for cost of shipping. I’ll check it tomorrow to ensure it’s solid and the heater isn’t shorted.

Thank you Chris, that is a generous offer, but I luckily have the mirror glass itself, and in good condition. I just need to readhere it to its substrate / backing plate. I think when one buys a replacement mirror, it is probably already attached to the plate.
I didn't try to remove the backing plate from the housing b/c I thought it would likely be brittle, but perhaps that will be necessary to best readhere the glass to it. I am hoping someone out there has done this before and will comment on their experience.
If it cannot be reattached, I may take you up on your kind offer Chris.