The old system the stations used a lot and I mean a WHOLE LOT more power. like 10 or 20 times what they broadcast today.. And still by the time it got to the RV park the signal was nothing to brag about.
Today you get MORE "Services" (Sub channels) with a fraction of the power at the station and as noted you either get a good signal. or you don't. there is a very very narrow "poor signal" band..
But the things that help
A better antenna. or RV use the Winegard Sensar IV (With wingman included) or a II or III with Wingman added with the Sensar Pro module indoor is about the best
or long term parked in the same point there are better options.
HEIGHT IS MIGHT... I sometimes tell the story of back in 1978 Trying out a radio.. My radio was 1 watt in the hand held mode (10 in the car) But this was hand held 1 watt. Little "Rubber duck" antenna. I'd be doing good with a quarter watt effective radiated Power I'm sure.
Well I was in Downtown Detroit. talking to a repeater tower in Adrian. MI (many miles away) and from there to Toledo Ohio..
An additional party tried to join in from Windsor. from where I was standing I could actually SEE his house but he was not making it. He had like 40 watts Effecice Radiated power at 30 feet and he was not making it. I had 1/160 his power and I was making it.... From the 21st floor observation deck of the office building where I worked.. HEIGHT IS MIGHT. (This was VHF high-band Roughly Chhanel 6 and 8/10ths (not to be coufused with 6-8) or 146 MHz)