easy access timber company property that allows access will pretty much be busy, NF land that's easy to access or navigate will have pressure.... it doesn't need to be roadless to limit hunting pressure, it's pretty easy to get away from people in many NF areas, people don't want to deal with it, and just keep packing into timber company property.
it's gotten pretty ridiculous pressure wise, but there is still a ton of country with very light pressure all season. seriously, nobody wants to start covering ground cross country on NF land, it's a pain in the ass, constantly, but if you just accept it is what it is and don't feel sorry for yourself, you can have a lot of country to yourself to do whatever you want without hunter interference.
look at areas of NF land that isn't close to main highways that lead to the busiest parts of the state. the coast, between big highways that lead to heavily populated valley towns are your best bet, and as far west as possible... the NF land right on the coast is extra thick and nasty, go east a few miles and the underbrush isn't so daunting, and pressure increases on NF.
i have pretty much shifted my efforts into those areas, because i don't mind hard walking, but do mind the hoards of new hunters that watch BRO videos and chase you around bugling at you, or destination elk and copy Corey, even though he can't figure the coast out.
as far as the habits of roosies, like someone mentioned, they are elk, they act like elk, don't overthink that aspect... they don't have very big home ranges, so if you find areas with lots of historical elk sign, break out the topo map and try to figure out areas close that they will likely live (topos are essential tools for NF land roosie hunting, satellite images are largely useless in most areas) wind is trickier on the coast, because we have less thermals and more directional wind, but thermals still play a role, but that roll is mostly to screw up a decent wind

the country is really broken, which makes the wind a mess too... it's not that big of a deal, but you need to be patient sometimes when you don't want to be.
about everything has thorns, and you will too after opening day.... dense marine layers (fog) will soak the brush overnight, and walking through it will get you more wet than if it was raining... it's not always like that, but prepare to get soaked.... it's the little things that add up and people get frustrated, especially since you can't see the elk most of the time.... you have to just become desensitized by the little stuff, keep your head up, keep a good attitude, and stay in the game.... it's not that bad.
there is plenty of opportunity to do little overnight or couple day backpack trips too, so you aren't covering so much ground per day.
as bad as people make it out to be, it would take a pretty special elk tag to get me off the coast in Sept, i love chasing roosies. we plan on moving to Wyoming in a few years, and i will still come back and hunt the first week over here every year, regardless of how good of elk hunting i find, i like chasing roosies, and nothing will replace seeing those black antlers coming through the ferns or salmonberry, and the too close encounters.
if you have any specific questions, feel free to reach out, i will try to help as much as i can. i won't be very specific on areas, but there is a lot of good country on the coast, but anything tactical, i'm willing to share, i have done a bunch of it..... you don't need a guide if you didn't need a guide hunting elk in other areas. there are only a couple people in this state that are worth paying to guide.