That's a nice area. About a 5hr drive from Windhoek. Close enough to Etosha NP you should add in a day-trip through the Park. Go in either the south or east gate and out the east gate or south gate. There is pretty much just one main very rough gravel road between the two gates with side roads off to several different waterholes for game viewing. If you can work it into your day-trip have your PH take you a little farther east to Grootfontien and see the world's largest meteorite. We've stayed in Etosha a couple of times and to be honest, just a day-trip is more than enough. The only thing you might see in the Park and not out hunting would be elephant and lion but even those in that area MIGHT be out and about too.
Depending on where exactly in relation to Otavi, you could be in the low mountains or just the flat-lands or a combination of both. You're going to be at about 4000 feet above sea level in that area. If, per your Avatar area you are around the land of beer and cheese curds at around 600 above sea level, you WILL feel the thin air. Start getting some hiking and cardio exercise in. Also the humidity will be 5% or less. Take some saline nasal spray (not medicated, just saline) and put a shot up your nose morning, noon and evening. Will help prevent nose bleeds from the dry air. Long Sleave shirts, wide brim had and sun screen. The ground/sand there has a lot of quartz in it. As a result, the ground reflects the sun like water and you can fry very, very quickly.
Not sure what your planning for rifle caliber but if it's 308 or 30/06 or anything in between, I'd still stay with the 1" high at 100m and either dead on or 1" low at 200m. Your shots don't HAVE to be more than 250m unless you want to take the chance. If you're up in the hills/mountains, you'll have fairly decent cover for stalking behindand can ambush from high or low. If you're in the flats, there will be so many various species of acacia and camel thorn bushes and maybe mopane trees that it will be unlikely you'll be seeing game much beyond 250m. Your PH will be able to give you much better recommendations and DO WHAT HE SAYS! Most important thing is to PRACTICE, PRACTICE, PRACTICE off standing shooting sticks to 200m until you can consistently keep every shot inside a 4" circle MINIMUM. That 4" circle is generally the "vital triangle" of a springbok. If you can do that you'll be good on them all.
There are two "iconic" species in that area you should think about if you haven't already - Damara Land Dik-Dik, the smallest of the antelope species and the Hartmann's Mountain Zebra.
Also, be sure and STUDY shot placement. The vitals on all African antelope species are farther forward in the chest than US whitetails. If you shoot any of them "behind the shoulder" like you do on a whitetail all you're going to hit is liver and guts and you're going to very likely have a long rodeo tracking them. If you hit a zebra that far back, your chances of recovering it will be slim. Fortunately, if you look at some photos of mountain zebra, the aim point is actually printed right on them - tip of the chevron over the shoulder.
