Mites aren't the only concern when it comes to QT. There are a number of things that don't show up immediately (which is why we QT new reptiles for at least 90 days).

Proper QT isn't that hard just keep the new snake separate from your established snakes, and only interact with the new snake or your established snake(s) per day. Do this for 90 days. If you suspect that anything is wrong at any point in those 90 days reset the countdown.