In GTA Online I used to go into Task Manager, Performance, Resource Monitor and then suspend the process for like nine seconds or so. That usually disconnected me from everyone else and I was in a solo public lobby. Until others joined again, but that usually took a while. I haven't tried that in this game yet so I can't confirm if that works, but from what I remember playing this on console, it wasn't much different to GTA Online.
I'd second this as well. I imagine the next couple of days at least will likely be heavy with updates to try and get it stable for people.
Another option i've found if to get any item you can sell and don't want, and use the editor to set your mouseover set stack size to something absurd, like 999999999999, and then lock it. mouse over the item in your inventory, then go to sell it, then the option to sell all should change the value to reflect actually selling the amount you entered for the stack size. You can get way more than the $50,000 from the money cheat, and still have "unlimited items".
Why don't you test it and see if you get banned? Let us know