Right now I've got an Autoseeds SuckerPunch, a Mephisto SourBubbly, and two AutoSeeds Hijack in one Ecogrower in one tent.
In the other tent, Mephisto Skywalker & StrawberryNuggets were started 7 weeks ago. An Autoseeds BerryRyder, and Dinafem OGKush were planted a couple weeks later in the same tent.
Too many plants, but I crave variety.
The biggest single tent height difference is between Skywalker (4 ft tall) and StrawberryNuggest (a 1 ft tall, wide berth plant).
Everything is thriving.
Tangled roots aren't an issue.
The main problem with light distance is that some plants get too tall, even after topping and training. The SuckerPunch was topped and LSTed, but is now almost 5 ft tall and tacoing.
My experience is that even 40" of light distance can grow excellent plants, and that's about how far the StrawberryNuggets is away.
I'm willing to give up on optimal light distances to get more variety.