I have not tried this, but in the upcoming 5e campaign I am in, a friend is wanting to play a Ranger and was extremely upset to learn that the animal companion works the way it does (that is, effectively inert unless his character is inert for the round). Part of that was being somewhat drunk at the time he read it, but he's still very annoyed about it. I have advised him to take it up with our DM to see if some sort of compromise can be found, and have provided two different alternatives:
(1) Command is a Bonus Action. Essentially, this trades most Ranger spellcasting and dual-wielding for bonus pet damage, or the benefit of Help, or a few other things. Since the damage is largely comparable to an offhand attack for creatures of CR 1/4 or lower, this should remain balanced if TWF is balanced.
(2) As the OP suggests, Command as an Action with ongoing effects, only Command again to change what's being done.
(3) Combine (1) and (2) together--Command as a Bonus ACtion with ongoing effects.
I've sent the friend a message with these options detailed, and presumably either he or I will bring it up with the DM to see if it is acceptable. (Normally I would not think to do it myself, but the DM has...frustrated the friend with the sometimes-excessively casual/non-investigative attitude he's taken, so I've already been called on to help facilitate effective and clear communication before.)