2017 38EL King Bed Base

[karpcbk15]

We're in the process of adding a sleep number mattress in place of the mattress that came with the trailer. Measured and it's a King or eastern king as some refer. 76" x 80". I hadn't really looked at the base until I removed the mattress. The overhang on both sides is almost 12" each side of the slide base. That doesn't count the fact the flat wood base is only 70" wide. Pretty good amount of unsupported over hang.
Has anyone replaced the wood with a little thicker plywood? I'm also looking at boxing in the bottom of the two night stands for storage and mattress support. The 2nd shelve was inaccessible except when you slide the mattress to the side. Might look at installing a hinge on the top shelve so there is easier access to the 2nd shelve.