Dave, a couple of thoughts, speaking as somebody with moderate hearing loss (a hearing aid on each ear)…
Yes, the isolating ear phones sound like a good idea. That’s what I do with my FT-817 or MTR and it works well for me (except I could do with some more gain on the MTR, so stations less than S5 might not make it!). I probably appear a little rude to passing hikers when they get no reply to their comments though!
Usually I am also running a VX7 which has Yaesu’s funny waterproof 3.5mm socket, presenting a bit of a problem. And if anybody on 2m wants to attract my attention whilst I’m doing HF they need to shout really really loud! 
What I would ultimately like to do is go Bluetooth for everything, but there is no prospect of the hospital giving me Bluetooth aids in the short to medium term.
Another option you could investigate is a neck loop (or typically nowadays a pair of small loops that rest over each ear) with your aids switched to ‘T’, with or possible without an additional amplifier to drive them. I did look at this briefly and it seemed a possibility, despite potential for interference from the RF.
Also you should be able to use shoes on your aids for direct input via an appropriate cable. Unfortunately my Danalogic aids don’t have suitable accessories as the suppliers concluded they were a bit rubbish. Maybe you’ll have more luck.
What I do for logging when I’ve got my paper log packed away is I record the QSO on my phone. In another thread ([Audio recording][1]) we talked about this and dedicated recorders. Obviously there is an issue here with the earphones or whatever being plugged in, but perhaps some combination with a Y adaptor could work out? These are readily available, to allow two 3.5-mm devices to be connected to one socket. So maybe your “wing-man” could plug in a second pair, or it could go straight to a recorder (but then there’s the issue of getting the TX audio).
73, Simon
[1]: Audio recording