Don't mean to rain on your parade, and very much sympathize with what you're looking for. You might find it, but be aware that most savvy mariners would shy away from such an arrangement due to the insurance and liability questions involved.
I know of a guy who "held the paper" for someone in need, the boat sunk, he was responsible for the salvage, the cleanup, etc. Wound up costing him an arm and a leg, figuratively, and his 53' Hatteras literally.
It's a HUGE risk in these days of heavy and sometimes mindless litigation, dicey insurance coverage, etc.
Better to save your money for 6 months or whatever it takes, then buy a boat outright.