[DIYguy]

Since you asked.... I would (did) distribute the batteries and put most of them under the box between the frame rails. The truck will handle much better and "feel" like you are not carrying a load at hich centre of gravity. I would put some under the hood, some in front of the rear axle and some behind it. This will give you good weight distribution, a safer handling vehicle and the ability to use your box for other things. Yes, it is more work. A lot more work... but the better choice IMHO.

Cheers

 

[rillip3]

There's actually an acid resistant paint available for just such purposes that you should consider using. Some metal for structure, some plywood for the bulk of it, painted heavily with this paint (it almost looks like triple thick latex when you finish, to give you an idea). A drain seems like a good idea, but then again, that might just create a leak point that ends up doing like your motorcycle did.