The bolt holes will have to be enlarged if yu do that. The liner material is very thick. Have it sprayed beforehand and don't worry about the holes. You'll be in another two trucks down the road before those bare edged bolt holes make any difference.
Mike
2010 Cedar Creek 34SATS (The Beast) & 20k Curt Q20 roller slider hitch
2006 Ford F350 SRW,SC Powerstroke diesel Lariat 2003 Harley Heritage Softail (Hogzilla) and a wifey with tons of patience....
And what do the hitch manufactures say?I would check very carefully about doing it before due to hitch not fitting as tight, as told to me by Reese years ago.
I had the hitch and spray liner installed and the company that did the work seem to have sprayed after drilling the holes but before doing the full hitch install.