The battery box next to the engine is a novel approach. I am concerned that apparently you are not isolating the battery from vibration in the box. In the cantilevered box, next to the 2-stroke engine, vibration could be quite severe. I would feel safer with the box sized so as to allow wrapping the battery with foam. Then, one should protect the foam and battery from oil soaking.

The four cell battery weighs about four ounces. If you move it to its "normal" location behind the firewall, you would only have to add an ounce or two at the front of the firewall to compensate. All in all, with the increased risk for the battery, probably not worth doing for most applications.

I would also advise not mounting weights to a plastic or glass cowl in most cases. I have seen this cause cracks at the cowl mounting screws. It is safer to mount weights only to the firewall or possibly to the bottom of the engine mount. I have used long engine mount bolts on occasion, then mounted steel, iron, or lead weights to the bottom of the screws with another set of nuts. nc

I also no longer rely on stick-on weights (auto wheel weights.) The foam adhesive on these is NOT fuel proof in the long run, and these weights invariably fall out! My new favorite method is to cast my own lead weights in a small wooden mold, about 1 1/4 inch square x 1/2 inch high. This mold will produce a maximum weight of about 3.5 oz. I can stack these if needed, or cast a shallower one if less weight is needed. I drill one hole through the center of these lead coupons and hold in place with a 1/4-20 bolt through the firewall. You can tap the hole in the firewall or use a blind nut. Neat!

littlera