I would do it. I've got the house and wouldn't mind getting a bare boat charter for the cost of travel.
There are house swap websites.
I suspect there would be a few issues involved.
Insurance for example.
I doubt it a live aboard couple would be willing to let strangers use their boat. The systems are somewhat complicated and all their personal gear is aboard.
What might work better is if two couples have a house and a boat.
They trade both for the same week.
One couple may decide to use the others couple house, the other the boat.
In this case really personal items can be put away in a locked closet. The boat is just a weekend boat.
This may be the perfect time to launch this service. In the past I would have said the the people that have a big boat and house would probably just rather spend the extra 3,000 a charter would cost. Maybe not now.
I like it are you going to put up the website or can I?
I'll just sub it out to Saildog, he works cheap.