since you have air to the hitch, this is probably a very good choice
I don’t have one (yet) but are well regarded on this forum
On the orig owner thing, you have to be a bit of an investigator. Look for maintenance records and see if you can get copies that have a customer name and phone number.
Newmar redacted this info on everything they sent me when I made requests for maintenance history/records, but Freightliner left it visible.
Cummins and Allison might have records under the engine and trans serial numbers.
Also look for stickers on the windshield and door frame for maintenance reminders and recall campaign documentation.
If you could still get info based on the vin and chassis number that would be best, but I don’t know if Roadmaster records are still available. That would be a Monaco owners forum question.