8MB right now is not safe, it's too much, nodes will drop likes flies. Im dumping my node for sure at 8MB.
Do you understand the importance hence of a serious logical and rational (not rhetorical) argument of why these non-mining nodes are essential ?
You are going to make a decision upon restricting the use of a system, maybe based upon an argument (we need lots of non mining nodes for "decentralization") that doesn't hold water, and of which one cannot give, visibly, a strongly argumented proof ?