G'day
Hooligan, not sure I fully agree with your concerns re- the vehicles etc. because:
a) Presuming we're visual with the RWY (we're talking VFR, right?) then we can see if the RWY is clear and if not obviously should not descned that low. But if clear you could descend to 1ft if you chose... (I'm not promoting that idea, just making the point) then go around; and
b) I think the 500' rule does not apply when approaching to land (but ready to be told otherwise by this august body

)
Fabulous thread - best that we all think these things through before they happen, eh!
Edited to say: Bugg*r! - I see
FFF has beaten me to it