Your equipment will be fine and just practice your shooting from elevation or the equivalent of a pit blind
It can get real chilly in the evening and it is usually a little chilly in the AM but warms up quickly, so a warm jacket for camp and layers for the blinds. As the blind hunting will likely dominate, black clothing rather than camo is better. Antonie may stalk eland with you on request, so remember that and a little camo might be worth bringing if that is of any interest to you.
Bring entertainment, such as lots of reading material for those all day sits.
The chairs are ok but I got a lot of extra benefit from taking an inflatable pillow to sit on all day...my preference is to go out in the morning and stay all day until dark. Others might be happier with mid day returns to the ranch house but not my style.
You will need plug adapters in Namibia for recharging batteries (phone, camera). Antonie will provide them for you.He has Wifi and I was easily able to use it to email from my Iphone
Take a few practice arrows to loosen up with in the morning, or if you are annoyed with a bad shot and need to work it out at the end of the day. There is a sand mound to shoot into behind the lodge.
If art, crafts, presents, are of interest ( they sure as heck were to me) then you should either ask Antonie to arrange some time at the market town that is about 1/2 way to the ranch, and/or schedule some time in Windhoek after you arrive, to go down town and shop. There are a few good shops and there is an open air market that is vendors in a big lot. I have gotten many nice things in both locations. I have wandered around the downtown area shopping and never felt unsafe.
Camera with long distance lens capability. I enjoyed being able to perch mine on a tripod. I think that I left one there: please ask Antonie if it is still around. Everyone takes 100s if not thousands of pictures. Do it, you won't be sorry
Study all the pictures of animals that you want to take. If horn size is important to you then really learn what that means by looking at lost of pictures and find someone with experience that can coach you. Frankly, you will get a kick out of anything that you take but the more you know the better prepared you are to make those split second decisions.
Happy to answer any questions.
Steve