Keep us posted on how it goes, Gary. Be sure to cover the holes with some type of screening. I like to use weed barrier fabric...it's kind of a spun fiber material, not a "mesh" like screen wire...it works great. You can buy a lifetime supply for a few dollars...I was fortunate my wife had some left over from a garden project so I "appropriated" it for my use.
Do remember that you're going to have an anaerobic layer down in that ~4" bottom layer where water will not pass through but rather sit stagnant. I'm no expert...it might or might not matter.
Even though top watering can cause soil compaction it also carries oxygen down into the soil and helps to flush out minerals, baddies, whatever, too. All of my pots have holes drilled in the sides ride at the bottom and also in the bottom so I can completely drain them if I want to...and also so I can adjust the water level inside the pots as I wish by raising or lowering the water level in the trays.
Just throwing this at you for thought. Don't ya just love it when somebody thinks they know what they're talking about but yet has never done what you're talking about doing?!!!