I'll be adapting this design to work on the Ender 5 together with (among others) the M3D QuadFusion head. As such, Y-axis real estate is already at an all-time high as long as I keep the wheels on. If I drill the stock plate and mount the QF straight to it, I already lose 20mm of build volume on Y because the nozzle sits 20mm further from the carriage.
To compensate this, I am removing the inner frame braces and replacing them with L-shaped T-Slot inserts. I'm also raising my X gantry and bed by 25mm, making them level with the top of the frame and significantly increasing X-axis travel and adding some Y-axis travel in the rear, as the carriage wheels will now clear the Z-axis assembly. This will restore me to ~225mm of Y-axis travel and up my X-axis travel to a full 300mm, netting me 300x220x300mm build volume.
I figure I'll have no trouble remixing this, myself. The only thing I think will need any adjustment at all, is I'm pretty sure I'll need to re-position the belt stops.
My question to you is this: Whatever I decide to mount to this, how much further out from the gantry 2020 is it going to sit as opposed to the stock carriage plate? I'm really not trying to lose the Y-axis travel I just worked really hard to win back, heh...