Portable system help please


A mate wants an easily portable small 12v system, to run off a car battery, to give him some outdoor amplification for his double bass.
Seems that car amps would be the way to go maybe?, with a super efficient 10" or maybe pair of 8" pa drivers (any suggestions as to drivers please).

Needs to be able to run for 2-3 hours at a charging, preferably longer.


Follow Ups: