great work so far! incredible!
i have a few ideas for the texture.
I'm not sure if it would be suitable but might be worth looking at.
I have used a few 'anti chip' paints used on real cars, the one i used came with a special nozzle which attached to the compressor which basically splattered the paint on as it is thich stuff.
Its usually used under front bumpers and side skirt under the doors so stones dont chip the paint.
it might also be available in pressure packs?
also, another idea like using sand paper is anti slip or grip tape, found in hardware or marine stores. it is generally a self adhesive tape.