Don't put them on the slope. Put them perpendicular to the shoreline across the ditch (bottom of the trench) just out from where you have them marked and about 20 ft apart. 3 ft of water under them and leave the holes as is.

This will give you a funnel from the raised bottom to the right to shore but with great change of depth. Small fish will get inside and large fish hang around the edges and over , under and between.

I have depth concerns with the concept and area. For a large part of the growing season - May- Sept. the 12 ft area may be to close to the thermocline for fish use. Also the small fish that would use the inside of the structure will not be in those depths (6-10 ft) during that period. Small fish gathering structure is better near where they were spawned and in 4 ft of water where they stay and feed. It is the small fish that attract the larger fish. Further if the structure is deeper than light penetration the plant growth on the structure will be limited.

An ideal place would be where the structure gives good change of depth and acts as a funnel or highway from the spawning/feeding area to deeper water in water about 6 ft deep (2 ft under and over the structure). This all assumes you will not be using pelagic fish for forage (shad/herring) in which case other options may be better.