Re SA tour, we need to ensure change later are made but that it's not unrealistic change which is then not appropriate and isn't in place come Autumn and the 6N 2019.
All Lions players excluding Sinckler, Daly, Marler & Te'o NEED to be rested. Hughes and Ben Youngs can be added to that list. Hughes, Youngs and Lawes will all be recovering from injuries and I do not think rushing them back will be appropriate.
I think the best way to look at appropriate changes is looking at positional blocks and trying to balance experience off with youth. We don't want a 1998 Tour from Hell, we need senior guys in so that the new lads settle in and can be at their best. Obviously there will be additional players also as we need a bigger squad for a foreign tour.
In addition to all those players selected for England throughout the 6N in the squad the following lads need a shot:
Genge, Ewers, Tom Curry, Ben Curry, Jack Willis, Dan Robson, Ben Spencer, Manu Tuilagi, Joe Cokanasiga, Jason Woodward, Sam Hill, Sam James.
There will be others, but those spring to mind.
I'd keep Hartley, Marler, Launchbury, Robshaw, Care, Ford, Brown all in the squad for some off field leadership.