Tolerant gateway_icmp monitor?

Create a new monitor, with the gateway_icmp monitor as the parent. You can then adjust the polling parameters to suit your needs. I can't remember the default, and no access at the moment, but I think it is 1 poll every 5 seconds, and fails if no response after 16 seconds. This seems pretty resilient to me. If you are getting flapping with that, I think you have a bigger problem you need to sort out instead. However, you could try changing the timeout to perhaps 31 seconds. That effectively allows 6 polls to fail before failing the node.