Nice pickup on those Art primes. I've used both extensively over the years and yeah, the 85mm is basically a boulder but the bokeh is unbeatable. Since you're headed to the Oregon coast, you definitely want something with a top-tier oleophobic coating. Salt spray is a total nightmare to wipe off if the coating isnt slick. In my experience, the Hoya HD3 is the sleeper pick for your specific needs.

• Hardened glass: They use a chemical process that makes it way tougher than standard optical glass. I haven't hammered one, but they definitely survive bumps and clinks better.
• Transmission: You get about 99.7% light transmission. You wont see any noticeable sharpness loss or ghosting on that Sigma 35mm, even wide open.
• Cleaning: This is the big one for the beach. The HD3 coating is super smooth, so salt spray beads up and wipes off without smearing everywhere. The B+W T-Pro is also fantastic because of the brass mount. Brass doesnt bind to the lens threads like aluminum does, which is a big deal when salt air starts corroding gear. If you're worried about vignetting, the T-Pro is about as thin as it gets. I'd grab these:
• Hoya HD3 UV Filter 67mm for your 35mm. It's usually around $75 and is built like a tank.
• B+W 77mm 010 UV-Haze T-Pro or the B+W 86mm 010 UV-Haze T-Pro for the 85mm depending on which version you got. Breakthrough is great glass but honestly, the Hoya HD3 gives you similar optical specs with better durability for the price. Let me know if you need help checking the filter size for your specific 85mm version.

@Reply #1 - good point! Salt air is basically sandpaper for your coatings if you arent careful. Unfortunately I had some real issues with that B+W T-PRO line on my last outing and was kinda let down. I really expected better performance for that premium price tag. I have tested a few of these on my own Art primes and found some disappointing trade-offs:

• B+W 77mm 010 UV-Haze T-PRO: The mount is almost too thin imo. I had a nightmare of a time getting it off once it got a little grit in the threads. The titanium finish looks cool but didnt feel as rugged as I hoped for coast work.
• Hoya 77mm HD3 UV: These are tough as nails but the coating isnt as good as expected for ghosting. I saw some weird internal reflections during golden hour which ruined a few shots.
• Marumi 77mm EXUS Lens Protect Solid: This was my alternative and it is legit. Way cheaper than the Breakthrough X4 but the glass is incredibly clear and it handles salt spray better than the Hoya. Just make sure you check your thread sizes... the 85mm HSM needs a massive Marumi 86mm EXUS Lens Protect Solid which can be hard to find in stock last minute.

Saw your post earlier and wanted to ask a quick thing before you commit. Those Art primes have huge front elements, especially that 85mm. Are you planning to stack these filters with anything else like a polarizer, or just keeping the UV on full-time for the trip? Also, is your main goal actual impact protection from drops or just a sacrificial layer against the salt spray?