I've got a couple SLR gas blocks, a set screw and a clamp on, in use with AR-15 platform rifles/pistols using slim handguards. I've got a 1/16 inch clearence to the bolt that holds the flat spring on a 300 BO build and seen no issue with it.
" I've only found one barrel nut that will work to fit a tube large enough to clear the obnoxiously sized gas block. "
Still not sure I follow, is the fitment issue getting the barrel nut over the gas block or the handguard not clearing the gas block?