Little tank, big headache

yeh this little tank is causing a load of brainpower drainage. i really cant make a decision on filtration, im seriously thinking about adding a sump to it and use one hole for drain and return or should i just build it as an all in one unit with back chambers??

i have got the lights, pump, heater, rock(live and reef bones), silicon now to get the glass collected lol. it is cut but i just havent got around to getting it home yet.

leave any comments about filtration ideas below please, your help is appreciated!!