4WD Self-drive ideas for Xmas?? Insights wanted..

Hi all, just joined this group, so forgive me if I don't read the backlog of
posts to see if this has been hashed out before. I live and work in
Kinshasa, so maybe I can reciprocate by providing info for any folks
considering visiting West Africa....

I am planning to do a 4wd self-drive camping safari over Christmas this
year. I have 3 weeks available, and there are three of us splitting a
rental. So far, we have found a 4wd Defender in Johannesburg, as that is the
easiest and cheapest destination from Kinshasa, and were initially planning
to do a quick trip up the border of Bots and Zim to Vic Falls, then move
west to Maun, then move north to Zambia and maybe even make it up to Malawi.
Then a long haul back to Joberg to return the vehicle.

However, after some more research, I am concerned about a few things....I
think Botswana will be too damn hot in late December to really be much fun!
So the entire drive up from Joberg to Vic Falls will just burn up time and
fuel (at 16 mpg and $4 a gallon, that will be significant). Also, I have a
stronger desire to see Zambia and Malawi than to see more of Botswana, so my
second-thoughts are to find a rental place near Vic Falls, and do our trip
northwards from there.

Can anyone give me some insights on a few things:
1. Can you recommend a good place for an affordable rental of a 4wd Safari
camping vehicle in Livingstone, Maun, Lusaka or somewhere north of Joberg?
Currently, we have a line on a 2004 Defender, fully rigged, for about $3800
for 21 days. We can shorten our time down to about 18 days, if needed.

2. Am I right that it will be too hot to really enjoy driving across Bots
during December?

3. What itineraries could someone suggest for our time period? We have
thoroughly explored Namibia and South Africa. Our hearts are looking towards
the northern part of SE Africa...Malawi, Zambia, maybe Mozambique. Will they
be too wet and washed out this time of year?

4. If we stick with our current plan...rental in Joberg and drive up through
eastern Bots, what 'must see' things are there along the way?


Thanks for any input!

--riverman