We did that style once for about a year but in Hydro. 4x4 trays full of grow rocks 40-50 plants each tray. The roots were all tangled together but held tight to the end. Yield was fine but clean up was a bitch.

Dirt farming is to slow for me. I assume you use an sulfer pot then to keep the mold down? Are you also using CO² to speed things up? How is the air flow for the middle plants?

Well good luck you have some work ahead of you when you harvest.