My suggestion would be to design in 'bolt on' backing plates with recessed bolt heads. This will help keep the shape of the mold halves, and simplify assembly with permanently fixed backing plates.
Make the printed halves identical, so you can print extra halves if problems arise.
I have to make more of an effort to source a 3D printer here in Indonesia. I have been lazy. I will be printing hard-baits rather than molding. This gives me the opportunity to improve the shape beyond 'mold-able', and with the added benefit of making my printed lures difficult to copy.
Dave