I have no "hands on" experience with a Red Trailer. I initially thought about buying one
I bought a 5' x 8' Northern Tool trailer I use as a utility trailer. At the time, with discounts, it cost $400. It is a very sturdy trailer and one of the rare ones that is five feet wide. It's a good base to build a 5' x 8' (or longer) teardrop trailer.
An upgraded 5' x 8' Red Trailer costs nearly $1,100 PLUS shipping.
That brings it into the price range of a custom made trailer with your choice of suspension, whether torsion axle or spring axle, your choice of tires and wheels, your choice on tongue configuration, and perhaps most importantly your choice of a custom frame size and load capacity.
For that large an outlay of dollars I'd prefer to have a custom trailer made. Which is what I did. I bought a Dexter #9 torsion axle and a local welding shop fabricated a trailer for me two days after we agreed on a plan (my plan) and price. I bought my tires and wheels from a local tire shop.
Bottom line, I think an upgraded 5' x 8' Red Trailer is

too expensive when you can have a

custom trailer built for a similar cost.