Nothing wrong with a C Channel frame. Most trucks use this type frame.
I have a 49 Chevy 1 1/2 Ton that has C Channel frame. It was originally a fire tanker truck. That C Channel frame hauled a 1000 gallon water tank on it. It was a cab n chassis when I bought it. I had a 10'6" x 8' flatbed built for it and I installed 2 x 10 hemlock deck. Made the rear bumper with trailer hitch also. I thought about mounting a goose neck hitch but I don't have a GN trailer anymore and the truck spends more time going to car shows than hauling anyway.