Contoured sanding pads don't really work with the RS2 as it is an orbital sander with a pad that moves in 2 directions, left-right & forward-backward.
A pad as you ask for would require a linear sander like the LS130 which only moves forward-backward. But then your baseball bats are not of the same diameter all over, so that would become a problem.
I'd probably sand your bats on a table using a random orbit sander like the ETS150 with an interface pad. Put thick cartoon on the table, maybe a few layers so you won't damage the bats, then stick a bat over the edge and roll it sideways while sanding.