I'm not sure darsben was being rude in the comment he made. Hats off to the welder/fabricator who felt this was outside of his skill set.. that doesn't, by any means, mean that people with experience in fleet work can't. A lot of commercial vehicles have fabricated bumpers and such. there isn't a lot of difference between fleet fabrication and RV fabrication.
If your frame rails are good.. a bumper/receiver can easily be fabricated on. It just takes someone with the right skills and money.
Thanks and good luck!
Jeremiah