They are not made to run for extended periods. Many have only bronze bushings for bearngs, and the windings tend to heat up pretty quick. But maybe a newer one, a light weight version, maybe ftom a Chrysler product (higher RPM) might be worth an experiment. They are made for short spurts of high torque, and are not that efficient electrically at high RPM. Between the starter motor and enough battery to run it, you will have some serious weight.
Back in olden times guys used to make homemade winches for their Jeeps using old starter motors and junk-yard gears.
I'll watch for your report on how it works out!