Sump design for 330L

[fishy-fish]

I have a large sheet of 6mm glass 1940 x 1180 and I'm looking to build a sump for my 330L tank. It will go underneath the tank in a metal frame stand. The stand is 2900 long and 550 wide. The gap underneath for the sump is 480 wide (inside metal framing) x 470 high and of course I can make it as long as I want. The main tank is 1408 long so will take up half the stand and in due course I will build a duplicate for the other side.

The first issue is allowing enough room at the top of the sump to be able to get in and out if needed. Ideally it would be great to double as an isolation tank so I need to be able to catch a fish if required. I was thinking a sump 1180(l) x 450(w) x 350(h) This will give me around 100-120 between the top of the sump and the frame allowing for a bit of poly underneath the sump tank.

So based on these dimensions, what sort of sump design should I look at? I'm still undecided on what i'll be stocking the tank with. It will either be another african tank or I will try my hand at a plec tank with a few corys and dither fish. I would want about 3000L/hr water turn over.

Here's a sketch of the set up...

Any advice or design concepts welcome!