180g DIY sump setup question

[jlts21]

I am currently working on upgrading from my 120 to a 180. With that comes all new plumbing (location of tank is moving and everything plumbed to basement) so I figured I would change some things up. I currently have a 75g DIY sump that I made and have a 40ish gallon acrylic sump that I want to use (in conjunction with a 100g horse trough). I'll attach pics with very crude drawing of how I'd like the layout (overflow into acrylic sump with filter pad, biopellet reactor and skimmer then draining into the horse trough filled with live rock, then return pump pumping back to the DT. While I have a good idea of how I want to set most of it up, my main question is how would I regulate the water level in the acrylic sump without the standard under-over then over-under-over baffle setup? Is a return section needed in the sump (ATO) if I'm draining to the horse trough? I would think that the horse trough is essentially the return section and I can put the auto top off to that.

 

[jlts21]

I figured if it would work I would just have a single under baffle (red line) between the filter pad section and where the biopellet reactor and skimmer would be. Then just have it be open and drain straight to the horse trough