The concern over weight distribution implies that you'll be riding hard. Triangle battery implies that you'll be doing this on a hardtail which sucks.
I would recommend a better bike with full suspension if you don't already have it, and put the battery wherever you want. Up high will increase maneuverability, up front will decrease understeer.
I put my MTB batteries either on top of the top tube or alongside it.
If you need more front grip, lean forward more.