You could, but mixing battery types is a bad idea. Each battery type has its own charge parameters. If you desire to add capacity, go with identical deep cycles.
You could use a marine style a/b switch. A battery would charge at home, switch to the B battery which charges while traveling.
2000 Cherokee 31BH, "flipped axles and raised",LEDs, solar, inverter, etc..aka "boondock ready". '07 Tundra 5.7L DC-LB, modded as well. C-co, 8/158th, AVN.
2000 Cherokee 29BH with 6V batteries, LED lights & 400 watts of solar power, flipped axles and raised. 2007 Tundra 5.7L DC-LB with lots of mods. C-co, 8/158th AVN Maint.