So I did this method on both the PS5 and PS4 version of the game. I realized that there is a generous amount of time given in between ringouts to still be able to get a double ringout. As long as you have one other player, you can set up a free for all against 2 very easy bots and your partner.
As soon as your partner spawns, have them run to one side of the map with you so you can hit them once. After you hit them, make sure they just jump/fall off the edge to get you the ringout. After they spawn back in, have them immediately go to whatever side you are on so you can do it again. Just rinse and repeat and if you do it fast enough, each time it will count as a double ringout. Just avoid whatever side the bots are on. You will likely have to go back and forth from side to side. You can do this in a 1v1 as well but obviously it will take longer.
Edit: This is a nice alternative and faster than the taz method who was also just nerfed today. It took me a 15 minute game and 3 minutes from the second game to do all 100.