Not sure why an opener wouldn't work? All that would get wet would be the arms.
As for the glass it was just to keep the stiles nice and large and simplicity. It could be one big sheet but it would have to be thicker and heavier. And it would cost more to replace when the mower tosses a stone through it. Never really considered anything other than individual pieces honestly.
I am sure LVL will work and being in the Great White North insulation is a consideration. But that is going to make one heavy door too. Mine are ... I am guessing but 35-40 lbs apiece? I carried them around from the shop by myself and installed them. You could use 2" think cypress or cedar and save a lot of weight.
Mine are on the garage and there was no issue with insulation of the gap where they meet. The stop against a stop at the top and I just made a couple of blocks with an ellipse sanded on them and attached that to the bottom of the doors. That keeps them even when they close. I thought about adding a strip to one door but that wouldn't help if they warped and there was the issue of the them closing a the right time and not hanging on the lip with openers.
As for hardware, the hinges are just standard gate hinges. My doors are so light I didn't need anything heavy duty for them.
Silly guys! We have to eventually move beyond our old dinosaur thinking.
For equal strength, compared to conventional lumber, LVL's are far lighter. (I've read, 50%, although that might be a bit optimistic.) And they can even be built as a hollow box, far stronger than lumber can... saving even more weight.
The "composite" example I drew... That's nothing but a couple of pounds of hard, stiff foam in that entire blue area... that's the total for both doors!
Composite construction also allows you to use just a thin, glued-on (if you want) lightweight skin, opposed to a thick one for insulation purposes as you mentioned doing. You know of much that is better for insulation than foam?
C'mon, Guys, it's the 21st Century.
We gotta keep up.
for some interesting reading on new material that is even more advanced than LVL's. It's good reading... follow it all the way through.