Three-pickup Squier Jag build - wiring problem

[thenamelessbook]

Hello everyone, long-time browser first-time poster.

I have some questions about a project I'm doing that is making my brain hurt, and any electronics help or advice you could offer would be greatly appreciated.

I picked up a Squier Vintage Modified Jaguar bass (the one with the '62 Jazz controls) a while ago as an all-purpose bass for my studio. It sounds okay but I wanted to replace the pickups and all the electrics to make it sound as good as it could for recording. However I then had the idea to dig out a cavity and fit something like a Wide-Range humbucker at the heel of the neck. So far so good, but I hit a problem regarding the wiring.

The current set-up has cheapo 250K/500K concentric pots with each pickup having a volume (on the 250Ks) and tone (on the 500Ks). I'd like to switch to a three-pickup variant of the standard Jazz wiring however as I don't use the tone much and would like to blend in different amounts of each pickup like a standard Jazz. So if I get CTS 250k/500K concentrics could I solder the P and J to the 250K sections and the WR to a 500K all in parallel and use the other 500K for a master tone. However I guess the pickups will see a weird load and sound odd with that configuration.

So am I right that this method will sound weird? Is there any other way I can connect up the three pickups with individual volumes and a master tone using only two concentric pots? And if I do, do I run the risk of either giving the P & J pickups too high a load or the WR too low a load to sound as they are intended? Or is this just a massive pain in the arse and should I stick with the PJ setup?