If the naish is an eps board then it's a define no no just sinking the boxes in ..... you must add high density foam and then sink in the boxes into that. Bridging the top and bottom skins increases the strength dramatically but at a cost of weight.
I would start in Cape Town. Stay there a few days and then travel down the garden route over the stay of your holiday. Its out of main season so finding accommodation won't be hard.
That way you get to see alot and do alot
Winds are not as hectic in Feb , not that I can remember