Great minds and all that! We removed our dinette a few years ago, and built a credenza/cabinet to suit our needs. We also deep sixed the euro recliner and purpose built a loveseat to round out the passenger side mods. Pics below.
Our credenza is 10" deep, about 78" long and 32" high. The top is 11 1/2" wide. The table is from the original dinette. It fits into a slot allowing it to slide in and out about 10" or slip completely out. There are position locks built in of course. We wired in a combo 110v/USB outlet on both sides of the table, giving us two laptop stations.
Don't know what a cabinetmaker would charge you, but you could get an idea by going to the big box store and price out upper cabinets. Cabinet widths are standardized in three inch increments. Heights are in six inch increments. So, for 78" we could have bought say, two 24" and one 30" upper cabinet to achieve what we built. Of course, they are 11 1/2" deep.
Give them the space you want to fill, and the bigbox will design and price a layout, to include top, for free. Then you install them. Your bigbox may offer installation also. Ours wants nothing to do with RV installs.
Fair Winds and Following Seas