Nexus Blitz would be the best for a shorter version of ranked/normals
If you take out the RnG part out of it with the events and you keep the core aspects of it (duo jg, adc/sup, and mid lane) im sure the game would be perfect it would be very short and even if a bad idea i think its something good to try out is it not? I encourage riot to at least consider it because im excited to see the outcome.