glush
While excepting you interpritation of rule 5 I have to ask how a gilder can go around on short final if someone is slow to clear the runway?
A rule that is imposable to comply with is a bad rule and should be changed.
I have no idea what the ATC situation is at the airfield you are flying at and my comments about "land after" instructions were aimed at some of the smaller airfields with full ATC. It could not be otherwise because it takes a full ATC unit to issue such an instruction.
Not withstanding the instruction if you think it is not safe you should go around.