Way too much thought put into this, in my opinion. This site is for getting the achievements. So do it the easy way, by putting "the Maw" on easy, log in a 2nd controller, throw on the infinite ammo skull for fun, burn through the level, get to the warthog and have the 2nd controller drive, have the account you want to get 10gs sit back and let the checkpoints drag them along, you don't need to get into the warthog at all, and with the 2nd controller you can flip all you want, just make it to the end of the level in time.