Sounds like you're set, but, for what it's worth, there's a $10 (ish) float valve you can get at Home Depot/Rona/etc that is used for furnace humidifiers that has no metal parts (all plastic). The feed line fits through a 1/2" hole (whereas you need 5/8", IIRC, for the Kent valves). They are open on the bottom so that you get an air pocket. I have one that has been in use for something like 12 years now on a tank (not the same tank mind you but has migrated from tank to tank over the years) and it has never failed. Float valves are the K.I.S.S. principle in action. (My float *switch* based topup, however, has had numerous failures in the two years it has been in use.)
http://www.homedepot.ca/product/repl...ssembly/948915
As for mounting in a baffle type situation, I'm not sure what Brad has in mind but some ideas that I've done in the past that have worked for me:
1) Drill a hole in the baffle, mount the float valve in there. If you happen to have access to a glass drill bit that is 5/8" (5/8" for Kent, mind you if you drill 5/8" and go with the Home Depot valve I linked to, it will still work OK, you can fill the gap with silicone if you want)
2) Take a half-pipe (or quarter pipe) and mount it to the surface and drill through that. Half pipe if flush mounting to the baffle, quarter pipe if mounting in a corner. Silicone can be used to attach.
3) An acrylic bracket that mounts to the glass would work well too.
Hope this helps. cheers