This Namibia part of the trip will work geographically?

Hi My husband and I are trying to plan a trip to Namibia for next year in September, October or November. (we are away from 1st september for 3 months) We will self drive. At the moment I am not quite sure if we will camp (I want to but my husband likes some comforts so we might mix) or just hire a normal car and use hotels. We are 60, very fit and love to day hike. Our travels usually include lots of day hikes, national parks, Unesco sites and searching for wildlife. We are not really into cultural things. We are retired and have as much or as little time as we want, we are very flexible. We will be also visiting Kruger, doing the garden route and going to Uganda to see the gorillas within this 3 months Please can somebody tell me if this Namibia part of the trip will work geographically and if I have made enough time to not be rushed, or if i have made too much time, to make the driving more enjoyable and to do the hikes and see the important things in the areas. Also if I have missed anything of interest that you might suggest we visit then please let me know and where to add it. I thank you for your help with this Day 1 Arrive Windhoek – collect hire car – get shopping – 1 night Day 2 Drive to Sesriem over the Spreetshoogte Pass – 6 hrs 4 nights 3 days Day 3 Hike up dunes Day 4 Deadvlei Day 5 Do the Waterkloof trail or the olive trail Day 6 Drive to Swakopmund - approx 5 hours 4 nights 3 days Day 7 Sea kayak with the harbour seals Day 8 Visit Walvis Bay Day 9 extra day to sightsee maybe up the skeleton coast to see the Zeila shipwreck? Day 10 Drive to Spizkoppe 2 hours 3 nights 2.5 days Day 10 Afternoon hiking Day 11 Hiking Day 12 Hiking Day 13 Drive to Waterberg Plateau 5 hrs drive 4 nights 3 days Day 14 Hiking Day 15 Hiking Day 16 Hiking Day 17 Etosha Park - Spitzkoppe to Etosha Okaukuejo 4 hours 3 nights Day 18 Okaukuejo waterhole Day 19 Okaukuejo Day 20 Halai waterhole 1 hr 30 mins drive 2 nights Day 21 Halali waterhole Day 22 Namutoni campsite 1 hr 30 mins drive 1 night Day 22 Drive to Windhoek 6 hrs Day 23 Fly to next destination