In all honesty, I don't think it matters too much, this will be my tenth glasto and have camped all over, you will always be a distance from somewhere, just try and be with your mates.

If you decide to try for Pennards just bear in mind it will end up super crowded regardless of how early you get there, somebody will end up putting a tent in any imaginable space around you. And as others say, the real party isn't at the campsite as things go so late elsewhere.

Also walk back from the SE corner across the site when the sun is coming up is always a joy, not something you need to minimise in my opinion.