Is 35’ and 50’ to long for RCA sub cables?

I am running a 75 foot subwoofer cable to the home theater subs and no issues. Make sure they are shielded. I bought mine from Blue Jean cables. Also, Mediabridge makes a decent shielded subwoofer cable and you can  those virtually next day service with Amazon Prime. 

Why not go wireless?

@OP,
You are between a rock and a hard place.
I would take @audioquest4life 's rec and get a good shielded sub woofer cable in RCA. I know Audioquest makes some inexpensive sub cables that include a grounding wire-which should minimize any ground loop hum.
Bob

I ordered two sub cables from Mediabridge on Amazon. 
One cable was 50’ and the other was 35’ and both were perfect for the length. 
Hooked them up loosely to see if there was any issues and nothing, worked great and sounded great. No hum!

Now I have to get them all working in harmony together!!!

thanks