As you know, I have as little experience as you do. All I can say is that I've done a few of these drills to sort things like this out, and a HUGE congratulations to you and your wife for practicing together! My wife and I did a few pool sessions before a recent trip to Cozumel, and while OW practice would be better, it's amazing how much you benefit from doing the drills together. My wife and I practiced sharing on alternates AND sharing a single regulator. While this shouldn't be needed in the field, it's a fabulous drill for working out buoyancy kinks. I confess it humbled me the first time a training partner got me to do this drill while we hovered a foot off the bottom of the pool. It was so hard to maintain my position while passing a regulator back and forth!
Anyhow, right off the top I'll say that there is training you can get on this sort of thing fro UTD and GUE. They both have recreational programs, and the UTD folks will let you use most of your existing gear. UTD sells DVDs showing air sharing and ascents and so forth. Consider watching them as well.
A few things to think about. I was taught to ascend horizontally. A little googling will reveal that many people think this is important for preventing DCS, and as a bonus at no extra charge, it is much easier to control your depth. An air sharing ascent in the horizontal position would be much easier with a 1.6m or 2.1m long hose. Insert debate here.
Ascents are easier when you have a reference line. I was taught to use an SMB. A little practice with it quickly reveals that buoyancy control AND managing a string that can entangle you AND dealing with it bobbing on the surface is more task loading than just looking at a gauge. That's without tossing in air sharing.
The aforementioned training and videos will reveal that some people advocate sharing responsibilities: one person deploys the SMB while the other tracks depth and stops. Debate this point: Do you need two people staring at their computers? If they are off by a few feet, is it lower risk for each person to stop where their computer says to stop or is it lower risk to pick one and have both people stop together as a buddy team? In the case of air sharing, of course, there is no debate, both people ascend as a team, so only one need look at the depth gauge and signal when to rise and where to stop.
It's true that an OOG diver may be panicked at the outset of the situation, but if your practice this I would hope that you get to a place where if it happens for real, you are able to calm down once air sharing has begun and the OOG diver might be the best person to track depth so that the donor is free to manage the gas and possibly an SMB.
Just a few thoughts here, no advice to speak of :-;
p.s. Should you choose to investigate long hoses, you will find that they work just fine with all your existing gear and it's really very cheap to make the switch. You need not invest kilorands in back plates, wings, and canister lights.