This has to be a common part requirement - should not need a salvage yard to resolve it.
Henderson's Line Up does a lot of Rv suspension reapir work - wonder if they might assist you in finding a source for the part. Normally they would have you come in for service, but under the circumstances they might give you some free advice.
Here's another place that claims to offer bushings:
Spring Works
I also see that Amazon.com has universal-type Energy Suspension sway bar bushngs - maybe a set of those would fit.
http://www.amazon.com/Energy-Suspension-95173R-Polyurethane-Applications/dp/B000CN7C88
Googling for sway bar bushings turns up quite a few hits - seems like one of them ought to be able to come up with a solution.