The "light duty" factory table in our terry dakota is hollow (like a door). Basically, 1/4 inch ply with laminate of your choice on top and 1/4 ply on the bottom. The width can be what you want. They then "frame" (fill out) the edge with solid spruce / pine that is grooved to receive a vinyl edge trim all the way around to "hide" the "sandwich". For "strength", they "strategically" glue in cross members in the interior to shore up the table and receive things like the tube holders for the legs. Overall, it is certainly not meant to hold a 200 lb plus person lying on it across a 36-48 in gap of the seating area. Ours suffered from this causing it to "fracture" in a few places which I then replaced broken components and reglued. To improve strength, I built a small support frame / stand that fits under the table when it is deployed in the "bed position" to shore up the middle of the table towards the open end / side.... ie the table when deployed in bed position is supported on three sides, the fourth has little or no support which is weak (poor) for heavy "clients"... :-)
Note, our table has collapsible "scissor" legs which provide no support when "bedded". On a "pipe" leg table, there might be "short pipes" that can be used to provide better support in bed position.