Scott:
I have extended a set using the cords Davis sells, but since you have the Cat6 already, you don't want to invest in the stuff.
I know the black UV resistant wire in the company kit is basically four or six conductor phone extension wire, the flat stuff, similar to what is on the sensors already. The kit uses a butt connector that the RJ series plug plugs into, on each end.
I asked earlier and started a thread on how long one can extend and if there is anything magical about the wire, that is does the sensor have a constant current or a voltage output. I recollect that anything up to about 150' should be OK, but there is a fudge factor due to length of run after 40-50' or so. Look for my thread to see the well informed responses to the question, including links to Davis' spec sheets that were very nicely provided. (and printed out by me but at another location).
The Cat cables use twisted pair, etc. I guess one could trial using those nice crimp phone wire connectors that do a quick and waterproof piercing of the cable and see what you get, running it in test mode for a few days to see if the readings behave themselves.
I think you could do both the sensors on the same cable since you have all those pairs.
I know you can attach RJ plugs onto the Cat6, and since there is no problem with capacitance or even grounding concerns, you should be able to let each end float and plug into a butt connector with a wee bit of dielectric grease on the fingers and a tight wrap with self annealing tape or even a layer of elephant snot over it to keep the moisture out, especially at the upper end. The lower end will just plug into the ISS.
But I defer to the experts who have already done this.... my sensors still are in the winter shade in the afternoon, with many weeks of subzero temps and now just yesterday a monster snow storm keeping me off the tower and doing the final install of my sensors to their new home.
How you mounting the sensors remotely? Did you figure out some what to use the little tray that they originally came on?