A 50' run is not long for coax (RG6??) and its attenuation should be minimal. That said, if you have marginal signal then anything helps. You are better to remove all non used outlets or terminate them with a Ballan as each is reducing signal strength. If you are going to add an amp then a Mast Head amp is the best else you are just boosting noise as well. You HD Home Run should give you three indications of overall quality:
- "Signal Strength" which corresponds to actual received power,
- "Signal Quality" which corresponds to the SNR/MER of the signal, and
- "Symbol Quality" which corresponds to the bit error rate.
Boosting the Signal Strength with an amp makes it "louder" but may not help Signal or Symbol quality. It can be a bit like turning up the volume in a noisy room, it makes it louder but no more intelligent.
I now run a single dedicated line from the Ariel to my HDHomeRun and it makes a big difference. You could also replace the RG6 (?) with RG11 to reduce attenuation (I ran a 100m RG11 Coax down a block from our cable provider to their CAL that then splits out RG6 to the Cable Modem, Pay TV box etc and it works well).
Now the issue with fluctuating temps if you put the HDHomeRun closer to the source will be "dry" solders. As they heat and cool, the solder may crack, causing permanent or intermittent failure. It is not hard to fix but you have to find and resolder these joints. That said I have an old HDHomeRun and the only issue I've had is with the PS failing to deliver the required (and substantial) power requirements after several years of use. This is seen as poor signal quality so that is also worth checking.