DIY Trailer welding project - what thickness steel?

Hi folks,

I have a project in mind and can't find an clear answer to my question.

I'm converting the chassis of an old caravan to a beekeeping trailer. It will have approx. a dozen bee hives - 6 per side, with a walkway down the middle. I have a pretty clear idea in my head on layout, but I can't figure out what steel thickness to work with.

Any suggestions?

The video gives an indication of what it will approximately look like.

Thickness depends on the design.
Also are you using square tube, rectangular tube or angle iron?
Will you use the steel as a stiffener within the trailer structure? If you do it can be lighter.
What welder are you planning to use? Stick, mig or tig?