The tail light mount (usually on the seat top) has an M5 thread if you want to change it from the one provided with your trike.
We recommend battery bags opposed to bottles as they use up less space and don’t take up your water carrying capacity.
If you have something particular you want mounted that doesn’t fit any of the mounts provided, you probably should have let us know, so that your frame was custom fitted to it. Don’t despair, as we may have a solution to help you.