Putting up a dual band (2m/70cm) antenna and am wondering about the best way to protect the fiberglass from UV damage?  It's going on a ROHN 34' telescoping mast and so I'd rather not have to service it every year or even every few years.

Any suggestions? Also, on this type of antenna (3 piece) should I also further protect the external connectors from water and if so with what? The antenna itself is 18' if that matters.

Mine was up 10 years and was fine.  

Find a coax connector sealing kit with 3M products and use that for the cable.

I seal the top of the external nuts where it meets the madt with coax seal to keep water out.

I found a 3M product for electrical connections that was really good and in fact is completely under water in my pond for a splice I had to make in my pond for a fountain. And it has been perfect for about 3 years now.  but it was kind of expensive and this application should only see rain periodically and I should only have two connections (100' LMR-400 with N connectors). It isn't so expensive that I wouldn't do it but the bad thing about making it completely waterproof forever is that you can't re-address that connection without re-splicing it.

Then again, maybe I just answered my own question lol. I'm gonna look that product up again

It doesn't require any additional protection. Painting it may only detune the antenna (depending on paint composition). Don't waste your time. It's designed to be outside for many decades.
The coax connector doesn't really need sealing either. It's inside a tube and protected from water. I didn't seal mine and it's been there for 15 years with zero problems. Seal it if you feel like it. Won't hurt anything.
Just read the instructions. They recommend a coax loop about a foot below the connector.
Very important: put some moly grease or Neverseize on all stainless bolts and nuts before installation to prevent galling.

I also put just a tiny amount of SS30 JetLube on the brass hardware when I assembled the antenna sections. It's not critical though.

I can absolutely guarantee you that any non-metallic Krylon color will NOT affect antenna performance in any way. I have performed anechoic chamber testing to confirm this as part of a project at work for a customer who wanted to color match antennas to vehicle paint.

So if it makes you feel better, or if you just want some cheap insurance, throw a little Krylon Fusion white on there.

Excellent! Wish I had access to a chamber like that. I heard that some paints are not recommended but didn't know the brands. What do you mean by "non-metallic". Is it color, composition or a specific type of paint indicated on the label?
How about Krylon clearcoat paint?

I'd be tempted to paint one of my verticals with non reflective dark brown color, to somewhat hide it from view. It's a short fiberglass, UHF/VHF vertical that will be used for camping.

The X50 on my roof is painted with Krylon camo brown. No issues.

It's nice to have one, but you'd be surprised at how well just getting outside and putting antennas on tripods works. It's easy to compare two antennas at VHF frequencies. The instrumentation antenna doesn't matter so much, and you don't care about absolute gain, just which antenna under test is better. If you need a ground plane just use some foil-backed down insulation board.

Anything that uses metal flake as part of the colorant. Example.

That should not be a problem.

Just wanted to thank you for sharing your knowledge, its amazing the people we have here.

No kidding. Excellent info.

My x200 has been up for 15 years with no issues.