LilJohn, dont give up yet. Solve the problem. It may be a lot less than you think. I know it gets frustrating but you can do it. Reposition the stock hangers and weld them in. If you go with all new rear springs go with the 60s series.
how big of a trailer/load we talking about? i have soft springs and when i haul a heavy trailer load the arse end really sags but i dont do that very often so its not a big deal. i think a pack with many thin leaves is generally the way to go, but you might need to give up some flex if you'll be hauing a trailer regular.
the biggest problem is a relatively flat spring here. its hard to build in load carry with a flat spring.
the ford and chevy springs will take a load better because of thicker leaves and still flex well because of the length, so i would go that route unless,,,,,,,, you went with a custom 10 leaf set-up, great ride, good flex and good load carry if they are built right. i did 7 leaf sets, but if i did it again i'd go 10. look into it, you might be surprised.