Tim,
I installed a W7FG 80 meter doublet here 6 years ago. I use bee hived feed threw assemblies here and I haven't had a single problem. Rain, snow, wind, winter or summer the performance is predictably the same.
My feed line runs very close to aluminum siding for some 20 feet with no ill effects wet or dry. You can expect similar results.
Going threw that PVC might be a problem BUT like you said
might be one of those ?s that cant be answered until you try it?
it might not. If the spacing is close to the 600 ohm standard just give it a try.
Be aware the failure event could be heat and smoke, or worse. I would advise a bee hived all thread feed threw.