Burch,
As an many decade automotive engineer and long time RVer, I am going to suggest two things that may be no more valuable than any other free advice.
First, make the habit of writing the mileage on every fuel receipt. Then later, you can roll them into a spreadsheet and get good answers. This will also help if you plan to keep the coach a long time. At some point the engine will need attention, and the jump in fuel rate will convince you.
Second, buy a Scan Gauge. They are a simple install and well worth it and if you use it to watch your driving, you can figure out what you are doing that is not doing you any good.
Matt