I believe that a tarantula needs its space.
I have put a few t's in big tanks and monitored their movements.
I have seen that they do roam the full space of the enclosure.
Tarantulas come out of the wild, may they be big or small , their natural enviroment is a vast bit of space.
If you are willing to look after them correctly , feed them correctly, then i dont see why you cant keep them in a large enclosure.
I use 4 foot enclosures for my theraphosa apophysis.
See attached.
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