EasyDCC SZBZ boosters have an optical input, suitable for connecting to the "Track" power output of other boosters. With the designated power supply (120 Watts) set to 20 Volts, the continuous output current is limited to about 6 Amps. That seems to be the sort of input you are looking for, although the standard booster's output is only driving a load of a few milliAmps, not powering anything else.
I know you want to simplify your outdoor wiring, but I wonder if you wouldn't be better off dividing it into two power districts, so one short wouldn't shut everything down? Two SZBZ boosters would exceed your total 10 Amp capacity requirement, and the equipment would be protected from currents of 10 Amps or more in short circuit conditions.?
Unless four or five locos will be running simultaneously on one half the railroad, two power districts capable of 5-6 Amps at 20 Volts should work well for you.
Is your track plan point to point, and does not have any reversing loops or wyes, so? there is no need to support reversing or auto reversing??
One issue with DCC you may not have considered is it "knows" which end of the loco is the "front". So, if you don't turn the locos, they'll have to run in DCC "reverse" to operate a train one direction on your railroad.?
I know some turntables switch polarity/phasing as they rotate, and don't need any other reversing or auto reversing. But, they are the only exceptions to needing reversing or auto reversing to run locos in their DCC "forward" direction both ways on a railroad, unless you physically lift the locos off the rails and turn them around.