Hi April . . . assuming that's a Scamp
trailer, the table width is 30" and most likely about 44" long, and you don't need a center support. I think Boler
tables are the same width, but you need not take my word on the size. If you do buy the trailer and it doesn't have a table to make a bed with you can drop by a Lowes, Home Depot or other lumber center and ask them to cut a 5/8" thick "MDF" (which is heavy but never splinters) or "A/D" plywood (which weighs much less and is easier to move around, but may have splinters) platform for you. All you'd have to do is measure the space, select a 4x4 foot or 4x8 foot MDF or plywood sheet, and ask them to cut it for you. Later on you could do some final shaping, add some hardware and turn it into a true dinette table/sleeping surface.
Generally the stores will require you to buy full 4x8 sheets, so you may have to lump it and buy the whole sheet, but see if you can get a department manager willing to make two smaller 2x4 foot sheets (which they also sell) and sell you the remaining half-sheet at some reduced price.
Some quick-fix alternatives include 2 2x4 foot MDF or plywood sheets cut to 30" or a 12' long 12" wood board (not particle or MDF board) cut into four 30" shelf sections. These would be temporary solutions, but they'd get you home.