Well here is what I did for my stove an wiring .
The water lines are 1 inch PEX . The insulation is a two piece Styrofoam block 12 inches wide and about 6 inches thick and came in 4 foot lengths.
The block had two one inch holes running its length and the water lines are sandwiched in the middle.
I got this from the stove dealer. I first lined the trench with black plastic .
I used a roll ten feet wide .
I just unrolled it in the trench and unfolded it enough to lay the blocks and water lines and folded
It back on top of the blocks. This gave me mutable layers of plastic liner .
And for electric an coax for my ham antennas I laid two 2 inch PVC conduits in the same trench.
One for the stove electric and one for the coax . I used conduit so I could add or replace things as needed later.
You mite want to do a search on out door wood stove suppliers to see what is out there.
Thro it wouldn't be to hard to home brew the Styrofoam blocks. What kind of stove are you putting in?
Hope this helps
Old F
To see my wood stove saga check out my web site.