Long tentacle anemones have decent survival rates in captivity compared to most spp. I have one in my 33g for over a year & it's doing great.
You should be able to keep a very wide range of softies, lps, even some sps (if water quality high & kept higher up) with your lighting set-up. Maybe try a clam. I have a Derasa under PC that's growing very well, although I do keep him high & feed him rotifers nightly.
Good luck.