Best solution I can think of is requiring the minimum ilvl of your highest unlocked raid that you can do at your level. So if you're 75 and have all of Ivalice done, you can only queue Alliance roulette with the required ilvl for Orbonne. I'm sick of popping into CT raids and seeing someone with no gear put it back on and then making a comment like "oh teehee, got Lota again!!! xd"