In my country of origin, a competiting dealer is selling them and I see them around the town. Mast is copied from Toyota usually, which is good. However with that low usage, it's almost certain that Li-on would be overkill. Lead acid does not smell horribly by just staying in storage. With that low usage you would charge the truck once in 2 weeks. If you keep the acid/water mix up and dont dry charge, there shouldn't be any bad smell.