I wouldn't rule out 5w lights yet. I use the solarflare 220 x2 in a 2x4x5 tent, i have them at 8" above the canopy with only about 1/8" of bleaching so far after 2 weeks. Since you have such a short height you'll need lights without lenses and there are not much quality lights to choose from in that category now. CLW is a solid choice, but you should also look at the lush lighting without the lenses that will allow you to grow bigger plants in a smaller place.
Best case scenario if you are able to put the light at 8" above the canopy and you use 6" pots maybe 1 gallon you can have a max plant height of about 2.5 feet with no room to spare. 5x5 is a huge space for only 5 plants you don't have the height needed for large plants in that tent. Perfect for SOG though.