Tinfoils get pretty big and grow pretty quick, so this basically aligns with the growth rate and size potential of you PBass. They should make great tankmates for PBass in a large enough tank, and as long as they are big enough to not be seen as a food opportunity by the PBass.
I love my tinfoils (although I don't have mine in with the PBass). They make great dither fish for other large fish / cichlids as long as the other fish are not too aggressive.
Eventually I want to have a 300+ gallon tank, and I was planning on PBass with a bunch of tinfoil and a catfish.
Yeah you should be ok, with the tinfoils, I've got 3 at about 8 inch, i used to have 7 of them but they got too big but now the 6x2x2 is coming they'll have a bigger tank. You should be ok, just keep an eye on them.