4 by 9 room help/ideas/brain storming

So I have "creative access" to a 4x9 room(a hidden/not so hidden false wall type thing). It's been a few years since I've grown, (had a 1 car garage last time) so this is a little different to what I'm used to and could use some pointers/ideas.

What I was thinking:

LIGHTING

2 600w or 1 1k and 1 600w? ( I was thinking 2 1k but thought that might be Overkill for the size?)
All in air-cool hoods


COOLING

A portable AC unit just outside/backside of room that will exhaust out a window

A 8in fan tapered down to 6 to fit the hoods.(sucking hot air from lights OUT) possibly a filter at end.

2 oscillating fans to keep air moving on either ends of room.

MEDIUM

I've used Coco In 5gal pots but with the lack of room I'm thinking a:
3x8 tray with ebb n flow system (kinda new at that so some pointers would be greatly appreciated)

NUTRIENTS

Canna Coco is what I used with Coco...can I use it for trays? Saw very good results in Coco so would like to stick with something that works with hydro ...any suggestions?


ETC

How many plants should I have in such a tight space?

Any suggestions on a good ph/ec meter?

Thoughts about a single 1k light with light mover?

Anything I'm missing anything?


Pic added of rough blueprint of room...

have your filter as your intake, and your fan after the filter and the light, in other words, have air coming in your filter, then through your light, then through your fan.if you have ac running, the filter is going to be more for odor control than for cooling, so just make sure your filter is big enough. i use a 440 cfm phresh in a 4x4 tent, and its just big enough to control odor well. for the area you want to use, i'd suggest something rated at twice that or a little more

If you go with leds you will not need sun glasses. Also they direct 100% of their output directly onto the canopy

The several leds I mention below all are the equal (actual umles) of a 600 hps

A lot less heat, too

An Amare Technologies P3 easily covers 2 x 4 (x 2). Also Fluence VPRx, or COB DIY, or Quantum Boards

I would use 2 600w lights in that space if it was me, or go with a cob setup. As far as cooling and ventilation goes your right on. I'm a soil grower so I can't say much on the hydro setups, but plant count is completely up to you and style of growing you could scrog 2 plants in it or run 18 and top/train them. All up to you man. A good economical ph meter is going to be a Hanna PH Checker or a Oakton Ecotestr PH2 or 2+ both are good brands and reputable units without breaking the bank should be able to find them for 30-60.00

You don't mention the height of the room which can make a huge difference in dissipating heat and the pic/sketch you uploaded doesn't make sense (scale-wise) for a 4x9' room. Is the area you're planning to use 4x9' or is the whole area in the sketch 4x9? Just asking as my room is 4x9.5x7.5'H and there's no way I'd consider running 2x 1000's, cooled or not (maybe 2x 600's cooled hoods and AC). I'm running 750w of high efficiency COBs at 1400ma and cool it with a 4" incoming and 4" exhaust inline fans, they cover 3.5x8' of usable space and make it a breeze to keep temps 78-80f year round.