Just got back from 3 weeks in s.Africa We too rented a LR but a more cushy model to get us from place to place. Used Shindzela in the Tamboti abutting Kruger for 5 days, then 3 days in the Tembe Elephant park..the other time spent just tooling around a circle from Jo-burg, Panaramo Route, the two safaris listed above, then the coast/St.Lucia, the Draks (Royal Natal NP and Golden Gate Highlands NP) then back to Jo-burg.
I too read about the weight restrictions before flying out and simply had 20 pounds of photo gear in a BigPocketsVest...during boarding SAA noticed no bags were being weighed and no count of actual bags carried on the person. But with us thinking the weight limit would be rigidly enforced we did keep the carry ons to 18 pounds or less; even out checked luggage was less than 28 pounds per person (including the luggage itself), we come from a backpacking background and get by with little clothes though we took and used down parkas and down pants (cold cold cold in the highlands even in an African winter, and s.Africa dwellings dont have central heat like here in the US).
Took a laptop too. Fed the pics into it off the cards nightly, then backed them up to an external HD, formated the cards for the next day.
Most used lens, the 300 2.8 + 1.4 TC after the sun came up strong, without the TC at the beginning of each days ride through the preserve.
Also took the Tam 150-600. It's a great lens too just for different purposes. There is no way it could have grabbed this little guy:

IMAGE LINK: https://www.flickr.com …icineman4040/14374818303/
African Barred Owlett
by
MedicineMan4040
, on Flickr
Many hear at POTN have done multiple trips to the continent, me the noob can only offer one piece of advice--lay the camera down once in a while and just take in where you are.