We don't worry about who records what, or when, at my house. I only have two rooms and rarely is there somebody in both rooms. You can go to Record Plus to change the tuner thats defaulted to record a program.(In dual mode, whatever tuner is doing the recording has to remain on the channel that's being recorded).
Man, don't expect to get the installer to do anything for free. He's struggling to get his route finished and just to survive as it is. Offer him a bit of cash and he might run the line for ya. I'd run an easy line for 25 or 30, and split it off the backfeed. You wont be able to get a completely seperate room that way, the line would be a mirror of one of the two tuners.