A muzzleloader is quite a bit different to shoot. First off, I have no clue what elevation effects our guns have. I do know our "zero" or relative correction adjustment for elevation drop is more than a rifle.
That said, the thinner air may have an effect a bit on a shot especially if you're looking at the 150 yard range of things. You're higher up, which means two other things. You're dealing with shots up and downhill and you're seeing more wind. Learn what your bullet does in the wind well....
You point of impact shooting up and down a decent grade will be significantly different. Practice those. Going uphill will shoot lower, going downhill will shoot higher. It matters little with a modern gun at moderate ranges, but our muzzleloaders will effect more.
Buy a cow's knee to keep things dry.
I fire a very well clean gun when hunting with a 54 cal flintlock with roundball. I use a touch of brake cleaner to clean the patent chamber and bore. I remove the touch hole and clean that with brake cleaner. I load the gun, then take a patch very very lightly sprayed with WD40. I do this to protect the barrel from the elements. some folk put masking tape on the bore I know of. I leave a feather in the touch hole with the pan empty. If I am hunting on foot, I have the pan filled and change it out every hour or so.
An avid percussion hunter I know uses wax around his nipple.
Frequently check the condition of your gun, if it's at half cock, if it has a nipple or powder in it. IF it still has a flint. If your cow's knee is still covered......
IF your hunting in one spot, glass the heck out of your shooting lanes to make sure there no surprise branches. I have a notepad to take notes. In low light, you can totally not see these things with a muzzleloader.
Get in the habit of doubling checking your equipment before a hunt, I have forgot caps, a spare load, priming horn, etc....
Not everyone hunts as safe as they should. These gun can go off accidentally easier than modern arms. Set triggers are safe, half cock is reliable, wedges stay in good, etc....
Put a bobby pin in your hunting tag pouch or on your clothes.
I always reload the gun after a shot, even if it sinks like a rock.... Bears love the smell of fresh meat.
If the gun get wet, make sure you got what you need to make it dry again, rags, a bit of alcohol, spare loads, etc....
I love lyman peep sights over scopes, if your gun has a peep sight, carry a spare aperture. Make sure you use a wider hunting aperture. I got a huge size one, around 1/8". I can shoot cloverleafs with that gun. There is no need for a small holes, they're horrible in low light.
Most muzzleloader elk hunts are during the rut, practice your calls and listening to them. although November seems late to me for that, but I'm a yankee from the catskills....