A rather productive day yesterday. Lots of experimentation and trial-n-error. Lots of web/eBook researching...

In the end, the Solid State Relay (SSR) was latching when activated rather than just momentarily shunting the garage door opener contacts. It did toggle the garage door to open, but I was afraid to leave it activated in a latched ON state through the entire door transition (akin to taping the wall button down.) So I yanked power after a few seconds.

I double-checked the garage door opener's control contacts 1 & 2 w/ a multimeter and read both ~36VAC and ~16.7VDC. I have some ideas to run down on this, but for now it simply made more sense to go back to the tried-n-true mechanical relay and try to figure out how to overcome the initial bootup activation problem.