So much to unpack here...
First, to be pedantic about it, you can't be hearing RF hum. RF=radiofrequency - far above the 20kHz that @Dr_Feelgoood212 can hear. What you mean is the 60Hz hum that comes from fluorescent lights and the like.
Second, I too am thinking though the what action to take about a Pro-V pick ups and preamp. OK, mine is a V, not an IV, but the problem is the same. So, I am interested in anything you glean from your experience. My current thought is to install these:
So your bass has a hum
But I have also been thinking about thunderbuckers and Seymour duncans.
One day, I will get past thinking and move on to action.