Double Offset Back Rivet Set
MYO and get exactly what you want - I've probably made 25 - 30 "custom" back sets over the years.
Shown are a couple of "Double Offset" versions.
The hidden "trick" with these that make them easy to use is that I counterbore the driving end to a depth of .032" and ~ diameter of .063" less than o.d. of set (at the end - sometimes I just taper the shank near the end to give better access to the rivet). This "recess" at the end, "captures" the rivet shank - and, as long as positive driving force is maintained, the set will not "slip" off the rivet as it is being set. I've driven two airplanes worth of rivets - no slip offs yet.
If you can't counterbore the end of the set, a universal set (for -3's) can be used, just not a reliable as a counterbore, and leaves shop head with a bit of a crown.