One 120W driver is definitely plenty for that space, I ran a 2x2 tent for over a year and usually had to dim it in earlier flower and def during veg. If you want better spread then I suggest actually getting 2 boards, and the Slate double heatsink (actually just getting 2 regular slates then u could mount them side by side instead of end to end) and running them @ 60W each. Same wattage, double the diodes, better efficiency. If you get the 54A driver then you would run them in parallel, if you get a C series driver then you could do them in series. I blame
@Rocket Soul for getting me hooked on this type of setup. I am up to 18 boards now (fourteen 288 v1, three 288 v2, one HLG65) and have an itchy finger to order one more v1 board for my veggies tent.
[edited - miscounted how many boards i had earlier]