The porta-roofumbrella plus a string tracker is the way to go. I found the string tracker pulled my arrow down a couple inches at 20 yards which made dead on aiming with the 30 pin doable.

Last year I hunted in a downpour and had shots at pigs and shot a nice sized coyote. Three of the coyotes came stumbling in durring the downpour as if they just new no human in their right mind [&:]would hunt in such weather.
In hind sight I should have left do to the lightning and thunder, but darnit season was almost over[:@].