I just opened the P89C51RD2 datasheet (2002 Jul 18) in order to run down on the OP, quoting the datasheet how to set the Timer2 into Programmable Clock-out mode... to be surprised, IT IS NOT THERE!
The T2OE bit seems to be present in T2MOD SFR, but the description of Clockout mode is missing, so is the item in the table listing the T2 modes.

I'd guess Philips screwed up Timer2 in this chip a little bit, and as this mode is rarely used, they quietly removed most of the description of it from the datasheet (forgetting to remove the T2OE bit from T2MOD description). Anybody has older dataseheets and/or erratas of P89C51RD2 to check?

The OP could perhaps consider using P89V51RD2 instead of the "C", the clockout mode is working there for sure (I am using it); or - as others suggested - consider using the PCA.

Jan Waclawek