Building a Rolling Wall, Step 1 The Base

I am working on a project to create a rolling wall for a local art gallery.

Wall will be 8ft wide, 7ft tall and 1-1/2ft deep. I’m planning to frame it with 2x4s as a standard wall, mounted on top of a metal & OSB cart, and sheathed in OSB (rather than drywall)

Here is a link to an inspiration buildout video:

https://m.youtube.com/watch?v=E3SrGzAsRBE

Now to the question.

For the base cart, I am unsure what metal to use.

I have watched DIY videos that suggested welding 2×2 square steel tube to make the frame and securing plywood or OSB to the surface. I think this may be overkill, and I don’t have access to welding capabilities.

As an alternative I am exploring:
Building the frame out of angles slotted steel beams and securing this to 7/16th sheet of OSB.

My biggest concern is the 8 foot span between the castors.

I will Of course be mounting 2×4 As a part of the framed walls baseplate. So this will further add to the strength.

Looking to the community here to provide some guidance:

• Is the 2×2 Welded square steel tube Overkill?
• Would the angles slotted steel be sufficient?
• Am I just over engineering this whole thing and should drop the metal all together an build the frame out of 2×4, top it with OSB, then frame the wall on top?

As a secondary question:
Based on your recommendation what method of fasteners should I use for the OSB to metal.