Definitely going to be a packed house. These are autoflowers, so you don't control teh size.. with photos you could do 12/12 from seed and it might result in small enough plants, but in this case i think it'd get full either way.
Can always prune some weak side growth when it gets compacted, if you have no other choices or extra lights etc.. It'll probably result ina better grams per m^2 outcome, because you can selectively remove the smallest stuff and should have more of the 'better' colas with more plants.
The light is all about the area of coverage more so than number of plants in that area. Whether you have 1 or 5 in that tent, if the canopy is "60cmx60cm the light needs are the same, which is usually the goal, less any space for equipment in your tent that is in the way etc...
With autoflower and a 18/6 light schedule or more you may only need 20-30 watts per sq ft depending on efficacy of your lights.. REad and react to the plants.. if internode (length between 2 growth nodes on stem) is too long, you need more light... if it is too short, you need less light. Somewhere between the two is the happy zone. keep some notes of how much power and distance from canopy you are using... once you find a good spot it won't stray far from that in future. (if you ever do photoperiods, you know you want 150% of wahtever works over 18 hours for 12 hours at same distance... or get it closer to achieve 150% of intensity at canopy -- assuming it can cover everything at that distance. -- proportional to hours of use per 24 hours)
REad up on Daily Light Integral. You dont' have to memorize the math.. just understand the relationships involved is enough. light is ordinal and measurable.. the plant can only take so much per 24 hours relative to local variables... (e.g. 35-40DLI for atmospheric CO2 levels and at least loosely controlled environment.. and 50-60DLI for boosted CO2 with tightly controlled environment) What's great about learning DLI is that it matters not about efficacy of lights, hours of use or size of garden... "My" 35 DLI is the same as your 35 DLI. One of us may be able to push higher than the other, but the DLI provide is apples to apples comparison, otherwise. (umol/s , PPFD, DLI. .. these are teh terms you want to learn to use -- just like "EC" is better to use than ppm or NPK values for fertilizer... good reasons why mostly to do with communicating with others, like DLI does.)