I remember a post awhile back about mounting an garage door opener on bike with velcro, where would be a good location to mount the opener without anyone seeing it?
My buddy took his garage door opener apart to just the circuit board and battery sewed it into a smallbag that could fit into any pocket. So it is maybe a 1/16" thick plus the battery, so he keeps it in his forearm pocket.
Many people are rewiring a remote into the high beam circuit. It is a pretty easy install. Just soder wires to the battery terminals and then jump the button contacts. Every time you cycle the high beams you open the garge door. Here is a link to one set of instructions there are several variations some with pictures just google around a bit.
For $20.00 buya mini remote from liftmaster, it is the size of the keyless entry on a car. I love mine, and you never know its there. I have even washed it in the washing mahine a few times (mistake) and after it dries out, it wiorks perfect!