Great trip.
Me and the boy (11yrs) did the latter 7 of these Munros over 3 days last July. I decided that once I'd got up on the ridge I wasn't coming down again until they were all bagged. So we did it with big packs too.
We started at Cluanie Inn and took the path up towards Glen Affric and then up to Bealach a Choinich where we set up camp in the exact same spot as you did. We did Ciste Dhubh in the afternoon. The following day we did the 3 Brothers with heavy packs, carrying an awful lot of water from the same spring as you found. We camped at Bealach na Lapan (no snow), which made our 3rd day very long and hard. We didn't hit the road until 8.00p.m. On the 'climb down' we took our packs off and passed them down to each other - I was concerned about keeping balance climbing down with such big packs.
It was a big walk and a fine adventure. I am especially proud of my son, quite an achievement at his age.
Really good to read your report and compare notes. (mmmmh! now I'll have to get plotting re. the other easterly 5 Munros!)