I hate shooting off sticks, in Africa at least I would go with one of several tripod type systems that also holds the rear stock for more stable shooting over those spikey bushes. Here in the states a couple years ago I bought my wife a Caldwell deadshot field pod, it supports the rifle front and back, the original short version, works great, very stable, they do make a standing magnum version, can't say if I would like it or not. The 300 will work fine I shot a really big Eland @ 250 yds or so Frontier Spartan 180 grain bullets, a friend makes them in South Africa, can't get them here, similar to a Barnes tsx with much deeper HP and differences in driving bands so it opens up faster and still retains weight for penetration. The Barnes TSX and TTSX are both fine bullets used the TSX in Africa, I'd probably opt for the TTSX versions if you want them to open up a little faster. Bunch of good bullets out there, I'd personally get an African anatomy book and look at vital zones and practice different shooting positions especially off hand if you can't find a rest someplace and the shot is not terribly far. One day I was watching training/shooting scenario's for licensing African professional hunter applicants at friends company and range, pretty cool stuff.