I would suggest talk to the Salvos about their trailers.
Many, many years ago I worked with a team that modified a old Civil Defence metal canopy trainer. Very heavy but modern equivalents of metal covered tradesman trailers exist now.
Was built so that the trailer roof replaced a tent pole in the marquee. Thus one side of the trailer was serving/preparation inside of the tent (with a tresel table) and the other side was cooking area outside of the tent.
The cooking area had a small shelter area that could be erected and was near a tent doorway for entrance. The drawbar with gas cylinders was outside of the tent for safety.
I cannot remember where the small generator & lighting bank were stored. Needed good lighting in the tent and the trailer had work lights inbuilt on the lift up wind doors of the trailer.
Tresel tables were transported on top of the trailer.
Now you could add a deep cycle rechargable battery, 240v charger & LED lighting
They never could work out the weight issue & so were limited in water carry capacity for washing/drinking. Also, in those days eskies were used with ice in the towing vehicle. Now you would have a 3-way fridge/freezer in the towing vehicle.
Then the infamous EMU Bus was built by Mitcham SES.
I would suggest the design will depend on what vehicles will be towing the trailer so that you get the weight correct and go for a tandem trailer if you can. More stable to work from when back jacks are lowered.