Maximize Cash from Relocation Bonus

I received an offer for an internal promotion that requires relocation. It is likely a short term assignment, and I would be there for 3 years. I'd like to keep my current house and rent it out. I have a low payment on it and it will cashflow really well.

They have offered a $30,000 relocation bonus when I move. Since I'm not selling my current house, I don't have the cash I need for a down payment. Unfortunately, this means I just need as much of that bonus in cash as I can get. I know bonuses get taxed heavily. Is there anything I can do to decrease withholding and increase the cash I get from the bonus? I thought about setting my 401k contribution to the minimum for matching for that month. Is there anything else I can do?