Gordo, Long term boat sitting is uncommon. Usually if a boat is laid up for the off season then it is being looked after by the boat yard or marina where it is kept. And normally laid up boats are not in an especially habitable state (water tanks
emptied, bedding bagged and stowed, boat covered w tarps....). Sometimes cruisers will look after each others boats for a short period of time...for example the owner needs to be gone for a few days, but for longer periods the boat is typically laid up (prepared for long term non use).
If you wanted to help defray some expenses, like slip fees
for example, then someone might be interested in that, but most I expect will still want an experienced boater aboard who at least knows proper usage of boat systems.
House sitting is far more common. I can think of half a dozen friends doing that right now just here in Panama
. No special skills required, just normal upkeep while the owner is away. I think pursuing this option is much more likely to be fruitful for you.
I also know people who "resort sit"...manage a resort/B&B/lodge while the owners take a break...usually during the off season.