A lead acid battery under the seat? I wouldn't do it. Thats a perfect spot for an agm battery. Whats your reason for not wanting to go that way? Cost? Whats the cost going to be when the acid fumes start eating away at everything. Or the weekly maintenance needed to make sure that doesn't happen.
2004 Dodge 2500 CTD 4WD FWC
1960 Jeep CJ5
Member CA4WDC, BRC, UFWDA, Tread Lightly
"The welfare of the people has always been the alibi of tyrants, and it provides the further advantage of giving the servants of tyranny a good conscience"
- Albert Camus