There is a technique you can borrow from home built airplane builders. Vacuum bagging. Ideally, you would get the special perforated separator sheets, but you could do a test run with just what you would normally have at home,
Place the two boards together with what ever glue you want. I would use a two part epoxy possibly a slow cure to give you time to get everything right. A 5 minute epoxy would shorten the time the vacuum stays on. If hole line up between boards put wires through and then tape down the ends so that no sharp points stick out. The advantage to vacuum bagging is that flat, smooth, level surfaces are not needed, so the ends of the wires will not cause an problems. Then put the boards inside a plastic garbage bag and tape the open end around the hose from the vacuum. For a test run I don't think it matters if you use a home, rug vacuum or a shop vac. Smooth out the top and bottom layers of the bag where the boards are and start up the vacuum. It will press the boards together with considerable force, despite any irregularity in the board's surface. If you have a strong enough vac, it will suck the bubbles out of your glue to make a better,strong bond. You must leave the vacuum on until the adhesive has set. Then remove the vacuum, cut away the plastic and the boards should now be one. You do want to be careful not to put so much glue on that it squeezes out from between and sticks to the plastic bag. Putting a piece of waxed paper above and below the boards may help prevent that.
If it works well for you, they sell sheets of separator material that epoxy does not stick to. And a better, stronger vacuum pump that is intended for continuous duty would be obvious upgrades. I believe that most still use common trash bags for the smaller items (obviously doesn't work for whole wings!)
Mike