I don't have any great suggestions, but, what about two ironing boards set up next to each other for a bigger space and stability? I have one of those white tables from Costco (or Sam's or Walmart), but realized it bows just a bit when cutting, enough to make me think my blade is dull. I had a piece of laminated board from IKEA leftover and put that on top of the white table and what a difference. Just make sure anything you use is perfectly flat and doesn't "give" when you press down on it.