umm... you want to do about 1-1.5 lbs of LR per pound.
usually if you have that much LR it will act as your filter, you just need to get some power heads in your tank to create a current so the water will be pushed thru the liverock.
you will want to get a protein skimmer.
i was going to go the way you were, but i decided to get a full refugium, a refugium is basically a small tank underneath the main tank which you put your skimmer, some lighting to grow macroalgea which helps mantain the tank, and also your heaters and etc.
my set up i am still using LR as the filter, just i dont like the look of a skimmer and everything hanging on the back PLUS with the refugium I have more water circulating just means a more stable enviroment.
plus refugium give areas to grow microorganism that are very good for your tank.