Rubber bands will require a bit of maintenance ( they stretch, snap, tear over time) HOWEVER their lightweight footprint, and abundance of is what makes it so ideal. I’d rather replace rubber bands often which are cheap and usually always available if I run out vs using a heavy battery strap which will add weight and look bulky.
I’d recommend what furious ̶p̶i̶g̶ pug suggested as well , the white firm foam that comes with the VTX03/atx03 is perfect for making a “battery pad” which will help keep your battery off those metal screws.
I would also recommend to go with nylon screws and bolts for they are much lighter. If u crash nylon screws won’t puncture the battery as easily as metal screws will.