Don't know if this is US or Canada registered. If you got at auction, then usually the title is still in the owners name as selling services usually just sign over the title but I don't register it with the state as they don't want to pay sales tax. Hopefully that is the case and maybe auction company has a copy. If not and you didn't make a copy before getting it transferred into your name, then plead your case to Motor Vehicles and if they won't give you the previous owner info, then you can request they ask the owner to contact you. Also you might see if it is in Gulfstream warranty system, or if you have found any bills or paperwork in the RV with the service providers name or the owner to start tracking down leads.
Gulfstream should also have at least the original selling dealer if it was not warranty registered, Have no idea if anyone will share info with you as an individual, but there are lots of paper trails to any vehicle.