I use Driftmaster on my Seaark. It's an aluminum boat with heavy extruded rails so there's a lot of material on them. I drilled and tapped for #10 fasteners, but for a fiberglass boat, through bolting with fender washers on the bottom to distribute the load would work great. I just happen to [refer the Driftmasters because when the rod holders are removed, the bases are very low profile and you don't have to worry about snagging lines, clothing, etc
For the rear, I had Glenn at Custom Marine Concepts buils an arch for the back that is drilled and tapped for 6 Driftmaster rod holders. I have 4 bases on each side of the boat. I've seen as many as 20 rod holders on a boat, but IMHO that may be a little bit overkill for a catfish boat.
2015 Seaark 1872 MV CC
Etec 90 HP
Bitter Gun Owner