As for applying the TWF rules for attacking with both ends of a force pike or shooting and striking someone with a rifle... meh, it's perhaps not strictly RAW, but it is definitely in the spirit of the rules as far as I'm concerned, but you're right, it's not RAW.
Now I'm having second thoughts about allowing it.
Without the equipment it's difficult enough that I'd *want* to allow it. And if a player invested in skills enough (say rank 5 in each) then they're clearly a master and should be allowed to try some new things, and are good enough to possibly pull it off. But the equipment mods suddenly start making it feasible at a lower level, by dropping what would have been 7P down to 4P...and now as a GM I'm stuck. One player invested a ton of XP, risked a lot and worked hard...and the other went shopping. So I'd have to not allow it in both cases to avoid the discrepancy.