I wrote about this before, but it may be of interest to you. A friend and I who play now and again, usually played CB fouls only, but found our allowable slop range growing a bit simply out of indifference.
We considered all ball fouls but decided that was really nit picking without a referee because we would have to stand up and watch ever so carefully on each shot to see if something touched an OB. So we discounted that idea.
Instead, we came up with what we thought was a happy medium. We play a sort of modified CB fouls only rule. We count an object ball foul a 5 point penalty. However, the offending player can continue to shoot.
You can further modify a rule like this to include this 5 ball penalty a part of the 3 foul rule if you like.
Just a suggestion that really worked well for us in finding a happy medium.