My 2 cents... other opinions may vary. I think most folks here who make them like the weight on the bottom like this picture:http://www.bulletweights.com/Portals/0/_product-images/mr-crappie/double-down-crappie-rig.png
However I think I've mostly seen the hooks go out 6-10" instead of 2" like shown on that picture. You have to get the lengths correct otherwise they'll tangle up. Some tutorials are more geared towards catfish or other fishing where you can use heavy mono line and that keeps those lines with the hooks more straight out and not tangled. I used smaller pound test so the line length makes more of a difference at least for me. Some people swear to that loop knot to prevent tangles.
The one I use is a Capps and Coleman rig and that has the weight in the middle between the top hook and bottom hook.
You may think.... why not use those old fashioned crappie rigs with the metal twisted thing and red beads? Those would provide water resistance and force you to use more weight to keep your lure vertical. You want as little water resistance as possible.
At 0.8-1MPH, I would think you'd want at least 1oz.... maybe 3/4oz would work but I don't think your lines wouldn't be vertically down. May have others' opinions on weights for sure. You want your line straight down so you know your exact depth and you want it as far from the front of the boat as possible. I tested this having the same double rig on a 16' pole off the front and another just down the side of the boat with a short pole. The 16' won both days. I've used 1 1/2oz before and then able to speed up my boat beyond 1MPH.
Less knowledgeable on hook size I bought them awhile back and not sure their size.