Any thoughts on the channel discrepency... YES
You also mentioned weak signal syndrom (Pixleated, freezing, drop outs and the like)
Most Digital TV (These days) is on the UHF band. true there are still quite a few on VHF High, and even a few on VHF LOW but most are on UHF.
The coax used in RV's is often "Lowest Bidder" RG-59.. this is a high loss cable so the longer cable to the REMOTE has far greater signal loss than the shorter cable to the MAIN TV.
Second differences in the televisions
And finally... This is an old story .. Airstream had that complaint back in the ANALOG days, One TV got good reception on some channels, the other on other channels, NEITHER got good reception on ALL channels.. What's UP?
Well as it happens a friend of mine is an engineer for the company that made the antennas for those RV's back then (Today it's a THOR brand and they use one of the big name antennas,, Jack or Winegard)
Well, turns out the tv cable was installed by electricians,, back then it was 300 ohm flat line,, they used good ELECTRICAL practice and spliced the 2nd lead in like you would ROMEX to a second outlet.. They did not use a proper SPLITTER which isolates the two lines.
Ken put in a splitter and all was good.
Finally.. UPGRADES to your system
I added the WINGMAN to my Winegard Sensar antenna
And the SENSAR PRO which is a multi-function box
Power supply for the mast head amplifier
Splitter (2 way)
Switch
Variable gain amplifier
Signal meter and scanner beats the diodes off the King Controls device.