OP, wht you suggest sems to much to soon to me.
My 8 yo (9 in Oct) and I have been camping alone since he was 6. We have gradually extended the area in which he is allowed to play when on site. I have always told him that if he sticks to his boundaries they will get wider, if not, they will get smaller.
This year on a large family campsite, he has been allowed to the play area (out of sight of the tent) and toilet block - approx 100 yards away. He was told not to go to other peoples tents or anywhere else without checking with me first. He did as asked. I checked on him from a distance every 20-30 mins unless he popped back for something.
We also went to camp bestival this year. I accompanied him to the toilet as it was a good walk. He was allowed to play 4 tents up and to the bottom of the slope - in view of the tent. He made friends with some boys 3 and 4 tents up. When he wanted to play around the corner at someones tent, I checked where, told him to go no further and checked him every 20 mins or so. Again he did as he was asked.
This summer he has begun calling for a friend on the next street. He is not yet allowed to the park as this involves crossing a busy road and has lots of bigger kids hanging about. Maybe next year.
I might get him a basic phone for christmas.
There is no way on this earth he would be allowed on the beach alone.
Seems a bit sad that he would be expected to go to the beach alone anyway. Why not go with him?