I have also fabbed my own hitch carrier, and will be making another in the next few months. What Rick said about welding up a bolt together store bought model is sound advice. You will want the 2" class III receiver for sure. If you stay light and weld the rack up, you should be ok. You could also have a heavier wall unit made out of aluminum if cash is not an issue.
'98 Dodge 3500 CTD NV4500 complete with a crap load of goodies.
'11 Rubicon Unlimited OME heavies, 285/75-17 Toyos
'07 Adventurer 10T with surfboard racks!
'75 Argosy (Airstream) 26'