Mustang,
I've always rejected mobile home feeders that were done with URD cable unless it was also marked "USE" and/or "RHW." URD does not show up in table 310.13 Also, the few times I ran across URD, I don't recall seeing the mark of a NRTL on it. I've also looked through the UL wire marking guide and "URD" does not appear there, so I don't believe UL even evaluates this type of cable.
As far as the 30 foot requirement is concerned, it is not a requirement of the POCO it is an NEC requirement, though some POCO's do write it into their requirements. If you choose not to do this installation to the miniimum requirements of the NEC, that's your choice, but you will be creating some liabilty for yourself.
Article 550 covers mobile homes in or outside of a mobile home park, so you should comply with the rules regardless of location.
As far as your question about running over to a second disconnect, there would be no need for this if the first disconnect was within the required 30 foot measurement. This rule has been in the section on mobile homes since at least 1978 (my oldest code book) and I've been told that it goes back to the original article when it first appeared (early 1960's).
Don't be sorry about disagreeing, thats what these forums are for.
TOm
