This one time we were sailing upwind but with the current, so there was a really nasty chop. my crew fell off the trapeze. I got so angry at that happening that i pulled her back on the cat with one hand.
It helps to start low. Have your wife try this... Hold the front beam, or if she can get a purchase, the corner where the hull meets the front beam is better. Then she needs to straighten her arms so she is under water. The buoyancy of her body will be working for her that way. Then she needs to pull herself up as fast as she can while kicking with all her might. The idea here is to half swim up. Go fast so she can use the momentum for the last bit. She may have the urge to stop as soon as she can get her arms and elbows on the boat, but that isn't enough. Her goal must be to get up high enough so she can at least get her chest on the boat. I have seen people flop themselves over one of the hulls using this technique and then basically roll onto the tramp from there.
Do you have a pool available? She can practice on the side of the pool. Frankly, if someone can't get out of a pool without using steps, then they are unlikely to be able to get back on a boat.
As for tool methods... A block and tackle secured about 1/4 the way up the mast and lashed to it might work. Your wife could unlash it, connect the lower block to her harness and then pull herself up. Maybe something like this could work with the mainsheet. Unhook the lower block from the traveller and hook it to her harness, but she would have to know which line to pull on.
Frankly though, if something goes wrong, and you are too hurt to help her, then the boat isn't likely to be upright anyway and I suspect she can't right it herself.
Taipan F16 - USA 213