I have done the front flat floor in my 2A with Herculiner applied with a stencil brush. I have 2000+ miles on it and so far really like it.
I did it over top of 2 coats of Primer 2+ coats of Epoxy Sealer and 3 heavy coats of Single Stage Urethane.
The new paint was washed down with Prepall then allowed to dry. I then took 220 grit paper and a small square sanding block (like 2" x 2") and carefully scuffed up every bit of where I intended on putting the liner. I had already taped off the walls etc. Before scuffing.
I vacuumed out all the dust then rewashed the area down with Prepall Allowed to dry completely. Then I put the Herculiner on with a 1.5" cheap chip brush I cut the bristles down to about 3/4 long I did not brush the material on so much as dabbed it like doing a stencil. This allowed me to control the texture. I had prestrained the material through some cheese cloth to remove the BIG chunks.
I put on two good coats exactly on the time schedule the instructions give and within 10 min of the second coat being applied I carefully removed the Masking tape as I was told once dried getting the tape off clean would be near impossible
The key is to have full paint protection on the floor before putting the bed liner on. That way if it gets damaged the metal is still protected. And rust can't work under it.
A close up of it under my pedals

Another shot of the drivers floor

An overall view

The shinny black you see is where the floor paint has been masked off to allow the Master Cyl cover and Tranny cover to meet up tight.