Well i have played 3, 4 Lan tournaments by using league multi. In my country, players have half an hour to setting up the config.
The first thing you have to prepare is the config setting, i copied it into a google drive files so there wont be anyproblem, just copy and paste into the setting files. I also use the pixel esp with yellow color and a toggle key, sometimes you could toggle for enemies info. Its impossible to recognize the super small esp dot with yellow color because of the highest digital vibrance i set up for my monitor.
The second thing is you download the cheat and build it normally, well the setting files are all bunch of notepads so it wont take lots of attention, cheating onlan is quite ez in my country without any kind of risk because we played in a private room and on b5 csgo anti cheat server, they think there is no cheat could bypass b5 so they dont need referee for players 😉 😉
If you played in tournaments have referee or lots of people watching behind, i dont think league multi is the best choice for you, you should dm jimster privately for a private build at LAN for stealth injection (if you really want to cheat)