You could just set each hive on two cement blocks and do away with the wooden part of the hive stand.
It's going to hold 2 hives. The hives will be above the cinder blocks. The reason for a 2 hive stand is to stabilize it in case the blocks start sinking. I'll be able to see the hives at the bottom of the field from the house so should be able to notice any significant leaning well before the entire thing can tip.
The tube with water will definitely work, but if you want something with more or less no maintenance required you could get some such as these on eBay.
I saw a 10 pack of those on Amazon for $12, but not before I bought a couple small levels. I'll mount them right on the wood.
I would not put wood chips underneath the hives...they will act like a sponge even when the ground might be drying. A sand and gravel mixture sounds good...a good amount of it might create a berm that is large enough to be above the native moisture holding ground and would drain easily. Dig down a bit into the native soil, back fill, and pile more to create a mound for the hive stands.
I'm going to try putting nothing down. I'll try some different types of grass in the area and see if it'll help by sucking up the water. I'll keep an eye inside to make sure no moisture is building up. I have screened bottom boards and will have top entrances, so ventilation should be pretty good. If that fails, I may end up digging. About a foot or so under the soil is hard clay.
If you know where the under ground stream is, try to place your hive right over it. Supposedly it helps the bees. Don't know for sure but in the archives of this forum are several threads about it.
My neighbor, who's family owned the entire area when it was a farm, recently told me about the stream and that his brother buried it. Unfortunately, he doesn't remember where it came out of the ground at or I would have dug it up. There is a small stream at the very bottom of the field where the woods start. I'm assuming that when he buried the source in my yard, it just wicks through the soil to join the stream at the bottom.
Like Allen F said, 2 blocks and 2x4s are going to make for some mighty tall hives with a few supers stacked on. 1 block high will probably be sufficient.
Are the hives going to be sitting directly above the blocks? If not, the 2x4s are going to sag, if the hives are suspended between the blocks on the 2x4s.
I'm using all mediums and am not planning on going more than 5 high. After I get these two going, I'll be building long hives. I've been working on a design to not only have the frames running horizontal with the hive, but to be able to attach another box at the end so it can be continually build or excess removed as needed.