tank looks great. always wanted to build one but cost to much for me.if your worried about it blowing out or leakin i would fill it to the top with water for sure if you already havent, cant tell in pic. i understand your extra caulk on bottom since they say most failures are in the bottom on any tank ada or walmmart brand.
id leave it up for a few days and if your really worried put your hand in it and slosh the water around. i would think thats more pressure than it will ever get sitting on a stand anyway.