More fighter-only feats couldn't hurt (as long as they're balanced), but really I don't see the problem with the Fighter. You're getting four more feats than anyone else, access to Weapon Specialization (which is even more worth he feat, IMHO, in an EL6 game), full BAB, d10 hit dice... About the only real problem is that you're still really hurting for skills. If you allow Able Learner for all races, or add more feats that add skills to your class list (like City Slicker) then you could get three instances of Open-Minded with those four feats, but that only works out to an extra 2.5 skill points per level, and you're stuck with no more than 4 ranks in any cross-class skill...
I'm thinking of showing up at a local D&D meetup in the near future (only, unfortunately, it's only really "local" on a cosmological scale...), and I've been thinking of even possibly running something. Usually for a one-off I'd do something a bit higher-level; I prefer lower-level stuff, but a lot of players don't get that many chances to play at higher levels... I may end up doing EL6, instead. I think that a one-shot with level six plus, say, ten or so feats could be really cool. I'm even tempted to try and do characters up on-sight, but I'm not sure it would work out (given a limited time-frame) even with EL6 characters being so much easier to run up than a 15th or so level character... (If I get my act together and actually run something I'll be sure and post an after-action report...)