Re:
Harder clear coats in a can are something I've been looking at. I've done two lovely *looking* DIY spray jobs this year, but of questionable (untested) hardness. Nicks during rebuild would suggest not hard a week after spraying.
There are two part clear coats in a can now. You break a seal on the bottom to mis the parts just before spraying. Considering this for my next build. They don't make financial sense compared to a professional job, but it's a job I enjoy doing.