To plan on using the FBO as a place to sleep because you’re too cheap to pay for a hotel is wrong. If you can’t afford $75 for a cheap room you probably shouldn’t be flying.
Not everyone is out flying for the same reason, or under the same circumstances, and cannot be expected to place the same value on $75 or on a hotel as you do. The OP is talking about being on the road for a *month*. For such a trip, the cost of hotels every night in every different location (money and time) might be the difference between getting to have a flying adventure and not being able to do as much or at all. Pilots, like airports, are all different.
Last year, I spent 12 months living like a hobo with an airplane, alone. Admittedly, I spent most of it staying with friends and family. But I spent a lot of time out exploring this great country, sometimes not knowing what airport I'd be at the next night. I had a tent and a sleeping bag, which I used wherever I could. Although I was willing to stay in a hotel if I had to, I tried hard to avoid them if possible. Partly because of the cost, but partly because there is no adventure in it, nothing new to be learned from watching cable TV in another Days Inn. Instead, I talked to people. Y'know, airport people. Overwhelmingly, I met interesting, kind, generous, curious, and understanding people. I've pitched my tent behind behind hangars and connexes and under beacons and next to the airport lawnmowers. I've slept on dingy couches, in beautiful free pilot bunk-houses, on the floor of a pilot lounge or two, and eaten morning ramen noodles from the FBO microwave. I've asked for advice from strangers in hangars, and gotten advice about the next little airport down the road where the owner is friendly and won't mind if I crash the night. Or about the next great destination 100 miles away. I've had nights of lousy sleep, but would not trade them for anything. "Camp at X06, so you can afford a night in KEYW" is my style.
Sometimes you can do research ahead of time (for airports with campgrounds or bunk-houses), but not always. It's easier when you're alone, and it won't work everywhere. Metro areas and metro airports are tougher. If there is a human to talk to at an airport, I will always ask first what is OK. Be courteous. Use your senses and your intuition. Look around. Will you be a burden or an annoyance to others there? Leave the kitchen cleaner than you found it. Be flexible. Be willing to accept "no" as an answer -- whether spoken or unspoken. Springing for a hotel has to be OK too, you have to *not* think of it as an onerous cost. A hotel room has a purpose, and of course it is worth the cost when it fulfills a need. And NEVER use "hotel cost" to make a safety-related decision (such as a go/no-go).