Here is a poor executed prototype of APRS, with sh!t-spec hardware and trash-level straps, but it decently serves as overall prove of APRS concept.
The prototype sling is not nearly as rapid as its name stands, but it is still adaptive. The supposed stand-alone sling with loop ends is connected with male fastex in the front, and rear adapter in the rear, obviously. In the prototype sling connection with rear adapter is performed with the DTMF, but certainly it is not an only option. Front swiwel is a cord loop with female fastex. Rear swiwel is a cord loop with DTMF.
Rear adapter is a small platform (made from wide strap) with a female fastex on it. It can be attached either side with rear sling end, to adopt to shooter. Right-handed configuration shown.
Front end of two-point sling is disconnecting from front swiwel, and connecting to the rear adapter – so one-point sling comes to existence.