Here is a 'Dwarf Cavendish' (which for all practical purposes can be regarded as equivalent to the 'Double Cavendish') fruiting in a pot. The container in the photo I would estimate is about 14-16in across and 18-20in deep. Granted, this was in Hawaii outside, and getting the plant enough sunlight is difficult indoors, but it can be done. You can generally expect any indoor banana to be somewhat etiolated, and therefore also potentially taller than an equivalent outdoor plant.
On a somewhat unrelated note, the banana nerd in me must make it aware that using the name "Mahoi" (which is a misspelled version of the Hawaiian word "mahoe", which means "twins") should be avoided as there actually is/was a totally different cultivar called 'Mahoe', it hasn't been seen in many years however and is thought to be extinct now (though it wouldn't totally surprise me if there is one or two still hiding in the forest somewhere out there in Hawaii). It had the same mutation as the 'Dwarf Cavendish' sport known as 'Double Cavendish' or 'Double Mahoi', but is/was a Maoli-Popoulu cultivar. Using the name Mahoi/Mahoe for the Cavendish cultivar is misleading as it has sometimes been erroneously referred to as a true Hawaiian cultivar, which it is definitely not.