Another thing to look at would be "Seal-tight" non-metallic conduit. It is widely used in the residential and commercial electrical market, water tight fittings can be used to make it as water tight as possible. It will last years in the sunlight, and with the fittings available, it could be configured in almost any way you can imagine. Pulling wire through it can be a challenge, but a fish tape and a little wire pulling lube and you're good to go.
Just another option to explore.