I’m in the process of doing mine also and I haven’t decided on a finish myself yet so im watching this thread with interest.

I can answer a couple of your questions though:

Cossieman did use hamerite smooth finish but it is still very thick compared to normal paint anyway. If you don’t use stone chip you would find it hard to appy without the brush strokes showing.

Waxoil is another hamerite product that repels water and provides a seal from the elements. It never dries fully and is best used for inside box sections ect, if you use it all over the underside its messy stuff and want give that bufty finish & dust and stuff tends to stick to it.