I went back and checked some of your old posts. You purchased your camper in April and have a few trips under your belt now. I also checked Keystone's web site, your Passport should have come equipped with a 30 pound tankT.
First, you will not be able to exchange the 30 pound tanks at convenience stores, hardware stores, and grocery stores like you can a 20 pound tank (like on your barbeque grill). They just don't exchange 30 pounders.
You live in Greenwood. Camping world will be able to refill your tank, as can any RV dealership that sells and services RV. I get my propane from Modern Trailer in Anderson, simply because they are only about 5 miles from my house and their price is as good as anywhere. I also pass an ACE hardware on my way to work every day, and they also fill tanks. Shop around, or do a search in on the internet for "propane refill Greenwood, IN" and you'll find something.
(I'm assuming you still live in Greenwood.)
About your usage, 30 pound tank. If you are running your refrigerator on Propane, and using your gas stove and oven, then your usage is pretty typical. I usually go through 4 tanks a Spring, Summer, and Fall cycle. Usage is much more if we run the furnace or do more driveway camps in the Fall.
If you use heat, don't be surprised if you go through a tank a week or even less.
I also only turn on one tank at a time, even though I have the auto switch over. I much more prefer switching tanks myself, than having both run out at the same time on a cold Fall night!
Once again, your usage sounds pretty typical. Tip: If your actually not using the camper (parked at home), turn your tanks completely off. Sometimes, (I don't know how), but sometimes, they do leak over time. I have on a couple occasions left my tanks on in the winter and come spring, it was empty. It went somewhere.... but who knows where?
Good luck. FYI, just pull the tank and take in in your truck or car. You don't need to take the entire trailer from a refill.