Whether that's true or not, I don't know. I'm quite sure that Rat contributors will make sure that these lawmakers are not paying out of pocket.
Supposedly many of the Senators are attorneys and it has been reported (I forget where now but it was on a local Houston talk show earlier this week) that their partner law firms will be reimbursing the wayward lawyer member Senators for their expenses while in New Mexico and contributing into a pool so that they don't miss a paccheck while on vacation across the state lines.