hmm well SPS in a small tank will be hard to do. SPS need larger tanks unless you want to break your back maintaining it. Lets just say its possible but it will be easier as you go up in water volume due to sps being sensitive to changes such as water temps or swings of any kind. Dont get me wrong ive seen it done but one thing you stated that makes it even harder is money..SPS is expensive and the lighting you will need is expensive I would recomend t5HO if you do halide you will probably need a chiller and thats even more money. Good Luck on the build I cant wait to check it out.