Yes, there is technically a way, but a regulator that would handle enough current would be too expensive and would need a heat sink and possibly a fan… not a good solution.
Could you drop the voltage with something else? Yes, you could use some full wave bridge rectifiers, and wire them up so they give you 2 diode drops, maybe about 1.4 volts per bridge, but you need 10 amp ones, and you might need about 4 of them… of course a one time expense… this might be ok, since they will not require heat sinks…
If you really want to use 2 of the 12v batteries (which should make charging simpler) this would be the way I would go.
Regards, Greg