Good idea in theory - I don't think it's inherently more exclusive than the extant P2P expansion - but the implementation would have to be very carefully considered. All other SLs let in at D23, generally requiring at least one player to fight their way through half a Tier before they're even allowed in; whilst the most immediate analogue might be to put a SL gate by the exit gate, so it can only be accessed after beating a T3 OCH run, but I worry that that'd get a little repetitive. I suppose there could just be an additional SL gate at D23 that only OCH purchasers could access.