Yep, clean them as needed, they dry real fast....
Also a tip. We've been in many of the Western States fire regions the last few years, where sometimes air quality is dangerous and even if not dangerous, hard on people with allergies. We also now carry the highest quality HEPA filter for an normal home heating unit that we could find. About $75 for two a pack of 24" X 24" filters. (3M product, sorry can't remember the one we went with. I called and talked to 3M Customer Service, and they helped me understand the differences between the different filters.). I took some shears, and cut those to cover the return grill on our AC (Note, Penguin II returns are on the grill on the bottom of the actual AC units, it's not a 'defused(SP?) return' unit as some of the newer higher end CC's have.). When traveling in heavy smoke areas, we green painters tap these cut filter's to the bottom of the return grill, on the outside. Nope, they don't look pretty, but on our unit, I could not fit them inside of the grill to hide them.) We keep the windows and roof vents closed, and will run the AC and or just the Fan, to filter the air in the coach. We can detect and improvement in under 5 minutes, when both units are on. Once we have the inside air cleaned out, and if we don't need the AC for temperature, we'll ther rear AC Fan running on low, to keep filtering the air. Reverse this to the front, when going to bed overnight, though my DW does not mine the white noise of the fan being on... I still prefer the quiet, so if not in a Walmart or Cabella's, we shift it the front zone at night
Really makes a difference in the quality of the air... And a bonus, even with the AC running on High, the noise is greatly return air noise is greatly reduced. We do realize that his reduction in noise, and improvement in filtered air, comes at a cost of lower air flow thru the units. And we're OK with this.
Last year at the West Grizzley KOA, this really became important. We were meeting family that had never been their, and renting cabins, and refused to cancel. Even with Going to the Sun road closed, we spent 6 days with them during the worse time of the fires...
A second time three years ago, we were at Eugene in Oregon at Oregon Motor Coach over the three day holiday for Labor Day. Multiple fires in the region, and no wind, made smoke so thick visibility was cut do 1/8th of a mile at times. Same thing, we did a few errands, but found this filtration technique, and we needed the AC as it was mid to high 90's that year, made all the difference in the world. (We almost got out on Friday, but a part that came from a vendor, was damaged in transit. So it was Tuesday when the replacement came in, and we got out by just afternoon on that year's visit
So that ends my tip on extreme smoke situation air filtration
Best to all, have fun, be safe,