Neither hand is specifically your main hand, it's just whichever your first attack is (ostensibly). That said, assuming you are using a light weapon in your off hand you bonus to attack from your character should be equal on both weapons, with only enhancments bonus really making a difference.* So, mechanically I'd say it ends up making no difference as you can choose whichever weapon you want to forgo an attack with and still be fulfilling the criteria of giving up your attack with the highest BAB, because it is equal for your first main hand and off hand attacks. And actually irrespective of penalties or other bonus they are always at the same BAB so you should always be able to choose either one.
*You could have weapon focus and use different weapons, and there are other situations too but generally people try to use the same weapon in both hands when TWF to maximize the effect of feats.
Eh, then it is still irrelevant because you have to have weapon focus with both weapons anyways so your to hit on both attack will be equal, except for possibly the ehancements to each.
And as I noted, the text says you have to give up an attack at your highest BAB. You get two attacks at your highest BAB, you have to give up one. Since you can choose either hand to be your main, it doesn't really matter which is which or if it's your main hand to give up the attack or the off hand. Sacrifice one of the attacks attack and proceed.
As to your concept, you can probably accomplish something similar to what you want with a little more ease.
May I suggest a Dwarf Slayer which uses the Ranger Combat Style talents to pick up the Shield Style line of talents. Then using Shield Slam and Greater Bullrush you can forcibly move you enemies and have it provoke for your allies.
What is the purpose of the hunter levels?
Seven levels of fighter (foe hammer) with the feat break guard lets you disarm, attack, bull rush, then trip as a standard action.
What is the purpose of the hunter levels?I think you misunderstand. With gestalt rules you get full progression in two classes every level. He's full lore warden, and full hunter.
He's replacing a bard/investigator as the party skill monkey, and off-healer.
I know what gestalt was, I was questioning your choice of hunter. It doesn't mesh with what I understand to be your greater goal. So my question remains, what is it you want from hunter (as opposed to other possible classes)?
A Ranger can off-heal just as much really, assuming you mean that he can use a wand of CLW. A ranger gets a good number of skills though I wouldn't call him a "skill monkey" because he's not good with many knowledges, of course the hunter skill list isn't much better.
Ultimately it is your decision, but my original question was trying to figure out why you were taking levels in hunter to gestalt with as opposed to something else. For what it's worth you might as well combine the fighter levels with levels in druid. More spell casting, same animal companion sort of progression. You get the good BAB of the fighter levels, and the extra feats.