2.5g reef stocking?

Hello! I currently have a 2.5g well established nanoreef. Tank stats when checked earlier this week were:
Ammonia: 0
Nitrite: 0
Nitrate: 5ppm
pH: 8.2
SG: 1.023
In the tank there's about 1" of live sand, I'd guess 3lbs of live rock, 1 xenia frag, 1 large hair mushroom, 1 astera snail, 1 blue-leg hermit crab, and 1 pink feather duster. The filter is a Tom mini dive-clean, which provides a sponge, a little carbon, and excellent circulation. Light is a little screw-in compact fluorescent 13w (I think) 50/50 bulb. No heater. I've been doing water changes every 2 weeks, about 4 cups of water.
Now, I'm wondering what else I can put in the tank. I'd really LOVE to get away with a little Catalina goby since I'm heaterless, but I'd definately settle for a limestripe or a yellow clown goby. I'd also like a Convict goby, but I'm sure that's out of the question. If none of these will work, are there any interesting inverts you'd suggest? What about sexy shrimp?
Thanks!

right now it's about 68F.
during the summer, though, it'll probably be hovering around 72. i've wanted one pretty much forever, but didn't want to sacrifice an entire tank for one...until now!

i think they'll get too big. i used to have one, and after he'd molt his antenna span was enormous. it probably would have touched the front and back of the 2.5g. :[