It does not matter 1 or more engines you have. Just imagine an ordinary placed tank on aerobatic plane, that flies directly up to the sky. Good aerobats has unlimited vertical perfomance, so I assume the will be no problem if you'll place your tanks right behind firewall, heading intake and pressure tubes up. Your intake will allways take fuel from bottom , unless you'll wanna do a roll ^_^
But the hight of an ordinary fuel tank ussualy smaller then it's length...