My thoughts are that since you'd be stealth that's a bit problemmatic if it starts to rain. If you're open and the mics are on a stand, while it takes some advance planning, it's no problem to put a stand umbrella up to protect your micsand wrap your gear in a plastic bag.
For stealth, I've heard that the condom method actually isn't as obtrusive as you might think...maybe you need unlubed lambskin rubbers for maximum sensititivty

. It's always worth trying out beforehand wiht your home stereo system to check your results...just make sure your stereo isn't ovulating.

You also want to contemplate the fact that you're maximizing a bad situation and even if the sound is a little degraded, it's probably gonna be alot better than nothing and I've always reasoned that I'm not gonna jeopardize my expensive gear for one recording, so better safe than sorry in terms of rain protection.
Perhaps if your mics have clips you could put them beneath the bill of a baseball cap that you're wearing.