Possible , yes, BUT are your baseboard heaters made for DC ? probably not.
I remember Mr. Zubbly was heating air with one of his mills. AC directly into a matched array of heaters., with a boatload of capacitors to make the mill starting up easier.
by matched i mean the resistance of the heaters was not so low as to drag down the performance of the mill.
and the resistance was not so high that the mill did not notice that there was a load on it.
Not that you cant use the generators to charge batteries, you can.
what was the voltage stamped on the generators?
At what rpm was the rated voltage?