That is what I have used before is the polyethylene and also use it for conduit, in fact I was gonna use some of the old stuff to put the cable to the sat. dish underground in. Cant leave it on top of the ground tho cause the bears love to chew it.
I used that sos tape then coated it with liquid rubber then black tape over that before. I have used shrink tubing for small stuff but not familar with (mung in therm)
I have the wires just hose clamped together for now, tried to find aluminum fittings to put it together when I was in town but no luck will have to look online and see if they have large enough shrink tubeing to cover it. Know any good sites for elec. supplies?