May be strange coming from another user who just today asked a similar question albeit for blind rivets......but I wouldn't even think twice here. Those look more than adequate. There will be so many more rivets in your future that you'll never be able to measure as precisely and have to rely on just a visual inspection or by touch only to determine acceptability.
In the course of building, I often repeat two mantras, both from Vans.
1. Your building a tractor with hand tools in your garage, not an F-22. (also rephrased often as "Your building an airplane, not a watch)
2. More problems have been created than ever solved by drilling out rivets.
I found it helpful to carefully examine other RVs and aluminum planes to create my own basis for workmanship that clearly was acceptable for flying aircraft.
Vintage Cherokee 160
SB Wings to QB stage
Fuselage in progress