Cliff, wait for the other guy and see what his move is and match it if you wish. If you want to avoid this dilemma, offer the gloved knuckle bump before the other guy makes a move and act cool.
I'm in construction, too, and I shake hands if someone wants to. They can see what I'm doing and if they want a dirty, sweaty hand, I've got one for them. I don't often wear gloves, so I don't have your problem.