I think your price for tires is a little low unless you only have 4 of them. I know for the size on my Class C that they run in the $200/piece range. I have 6 and that would be $1200. But by the time you ad environmental/disposal fees, installation and balancing, you are looking at an additional $150. Not too far off, but if you are trying to do a precise budget, it could make a difference.
Is your RV a diesel? If not, I think you priced the oil changes kind of high, esepcially if you are doing it yourself. The price at the ford dealership for our gas E450 V-10 is $50. And that's them doing it. Have no idea what cost of diesel would be.