I run a very open coop that is covered. We live on clay soil that never drains well. When the coop gets wet I always know it is time to break out the hay and cover it until the coop is sufficiently elevated that any water pooling underneath is a non issue. The chicken(silkies) hate hay getting...
I kinda like your thinking here, now if you could build a drainage channel that collected water and test it out to see if it burns your veggies or ornamentals, or build an adjoining raised bed on top of a pea gravel mat to use the run off for fertilizer might make for a complementary system.