Our Travel Trailer came with the Winegard Sensar IV HD Antenna, which you crank up and then can turn to tune in stations. We added the Wingman to increase signal strength. Next I installed the Winegard Sensarpro TV Signal Meter, which replaced the standard power supply and acts as a signal strength indicator, adjustable amplifier and wall plate power supply, it added specific search modes, eliminating guesswork. Also found a foam rubber clock, like the one you might use to train your kids how to tell time. I cut out the center with the hands and placed it over the ceiling crank so that once stations are found you can mark down their location then when you wish to change the direction of the antenna for a specific station or group of stations you know exactly where to turn the crank to align the antenna. Also the following web sights will allow you to put in the zip code of the location you are going to camp at and it will show the RF number and stations that can be viewed by your antenna and the strength of their signal and location to give you a better chance of locking on. And last I found that once the Sensarpro TV Signal Meter locates the most stations I let the TV search and lock in those stations, the TV seems to pull in more then I get by just selecting the channel. Be aware that not all stations are the common ones you are used to, many have an RF number like 45 and will represent channel 12 or Fox on the signal meter.
http://antennaweb.org/Address.aspx
https://www.tvfool.com/modeling/
Just spent 5 nights in a state park at location have used before. With all the above said and trying everything I got similer results to what you got. PBS was solid and a few other stations of little interest. The main local stations, national network would come in and go. If we move our trailer to another location, about 30 yeards away we get atleast 2 of the major stations and they come in clear along with several others. My thinking is to many obsticles blocking the signal and antenna not high enough!