FADEC225,
Depending on the Operational Rules, the maximum mass for landing on a rig will be satisfaction of the PC2 requirements.
At the very least that will be the mass provided by the lesser of: maximum certificated take-off mass; compliance with Second Segment Climb Performance (from the clear area CAT A performance graphs); or the OEI en-route climb requirement (which is identical to PC1).
Even if your State's rules do not specify these limitations, the operator (pilot) might wish to apply them - they are not (usually) punitive.
Jim