Laying the table flat sounds like a great advantage wrt crosswind.
Building your own trailer sounds like a really good opportunity. Many thots. A pro for building with a wider axle is that you can keep the table really low, possibly stack lighter loads atop it (depending on its case) and have a a shorter cable or padlock bracket to secure the table case to the trailer itself. Building a hinged grate that folded aside/over the table would allow you to get a top load that wouldn't threaten to scratch or buckle your tables case. Unless you slid the table case (or rolled it on some casters) below the cargo rack, you might always be unloading all your ancillary goods from the top of the rack to get to your table, and that might be superfluous activity. Cargo above the table would also need to be lashed, unless that top grate became a cage or basket.
However, trailers break and if your first try isn't so hot and you start running short on time to build the next one (as would be my challenge), I immediately would consider that if you can find donor trailers to mount your table flat to the top of them (like saw the roof bars off a burley bee) and then concentrate on maintaining a good build for cargo bracket, the lower volume of the existing trailer cabin up to the top of the wheels becomes a rain-sheltered, caged and load-centered cargo hold. This might also put your table case high enough to much more easily handle. I know that if I were regularly lifting a heavy load only 8" off the road, if I didn't flip it onto a dolly (or built in dolly wheels) -- I'd really piss off my lower back. That ergonomics might be convenient, along with the work flow of not needing to unload all the smaller cargo above the table before removing the table.
The length of the table case might quickly decide on using a pre-made donor trailer. If the trailer tongue isn't long enough you won't be able to put the center of mass ahead of the trailer axle.