It looks to me like the Fischman Powerbridge might be a good option for this build. They have two tele bridges.
There's a catch. It can be used passive (no battery) but the output looks like it will be quite a bit lower than regular magnetic pickups (-14db). That means you probably could not blend them. You'd more likely just turn them off if you're using the Fischman.
They have a pretty unobtrusive preamp that you can add (they say power chip). This would boost the signal enough so you could blend. I could not find the install guide but I think it would require adding a battery and maybe a battery box on the back.