One of my Kune Kunes has been scabby in the past - flakey looking skin. She is black and white and her sister is ginger but has never had any issues skin wise.
I queried this at the time and was told it was normal. A little concerned still i used some pig oil on her skin which ironically used on horses to keep the mud off them when they are being ridden out in muddy conditions and it stops the mud clinging to them and comes off easily. However, it was recommended for the pigs skin. I have also used olive oil on her - not in the sunshine though remember, and this she really enjoyed this. She still has flakey skin and they both scratch at the first opportunity and that's natural. In fact she's always had flakey skin.
The blistering - hmmm now that i can't help with.
best of luck.