Switch your gas block to a smaller one like an Odin or YHM. If you go with the MOE SL, (I assume your using carbine length) It adds a 4th slot on the bottom. Those slots are made for mounting Magpul items, so just grab one of the appropriate sized Magpul rail sections and mount the light there. Magpul SL handguards are open on top but the 3,6,9 sides are longer only. Make sure to use your handguard cap behind the gas block so you can put the handguard on the same way yours is mounted now. You can use your same gas block if you wish to retain your front sight, but the rail may be in the way and need to be trimmed to fit. Using a low pro gas block will work but you lose your front sight, unless you choose a new gas block with rail on top only, and use a MBUS front sight.