Found this searching google... Not sure what dimensions you are after. The U-Dinette table top should fit inside the U-shaped seating to make a bed???
From a forum post May 2011
"Okay, for those that are interested, here are the dimensions, in inches, of the sleeping areas in the Jayco 1207:
King - 77 long x 70 wide (based on slide out; could go 2-3 inches longer)
Queen - 77 long x 60 wide (ditto on a bit longer)
U-dinette - 80 long x 49 wide
dinette - 62 long x 36 wide
Hope someone out there finds this information useful."
I am assuming the 80 long X 49 wide is the total area for the bed with the cushions laid out next to each other after the dinette table top has been placed inside the seating area. Not sure why you are needing another large piece of wood to lay in there. The wood table top along with the wood under the cushions should already be in place after you do the bed set-up.
Roy and Carolyn
I claim Horse Creek Country in Southern Ill - Momabear is from North Texas
We live in King George VA
RETIRED DOD DOAF DON CONTRACTOR Electronics Tech 42YRS
"We're burning daylight" - John Wayne
2008 STARCRAFT 14RT OFF-ROAD POPUP with PD9260C and three 85AH 12VDC batteries
2010 F150 FX4 5.4 GAS with 3.73 gears - Super Cab - Towing Package - 2KW Honda EU2000i Gen
K9PHT (since 1957) 146.52Mhz
"We always have a PLAN B"