Marie,
With 6 tanks, are you diving doubles these days? I recall you like HP80s. I'm asking as I do not know if SM LP50s will cut it for your wrecks. Which I know you love. I don't think you did doubles class yet?? So 100+ cu ft should be on par with HP80 plus pony.
From your latest lake trip you wrote you left the pier looking like a worn out puppy. What was it about the four(?) dives that day that did it? Tank size? Swells? Long day? Exposure? I'm sure you've thought through what was hard. One possible option, can you rig up back mount in the water? Have the rig tossed in and then slip it on weightless. I'm not familiar with lake diving so I do not know the conditions.
There is always ice diving
. Any wrecks under ice you've been curious about?? Carry the cold all the way. Sit in a hut, gear up, drop down...? At least in my mind's eye.
Good luck in finding what you want to do. Sorry you're feeling beat up physically.