Hi, for far too long they have been housed in bare minimum sized enclosures, no way is a 4L x 2H x 2W (feet) tank big enough for even one adult, at least as the permanent home?
I would suggest a minimum size of 5L x 2.5W x 2.5 H (feet) but bigger is even better..
The species can live for 20 years or so, for anyone to believe they should be contained in the smaller size is tantamount to animal cruely in my opinion
If the animal/s are female they will require a decent depth of substrate for nesting, that being between 10 to 12 inches, so even if the setup was 2.5ft tall it doesn`t leave much above ground space, the species is quite adept at climbing, and they should be offered the opportunity to do that if they choose..
I would suggest that many "breeders" keep them in as small a space as possible, and if the monitors breed they will say it`s all the space they need (nonsense)??
This is my (male) V. storri, they get to around 16 inches or so, the enclosure measures 6L x 2W x 2.5H (feet) and he uses every square inch...
For two animals (V. acanthurus) I would advise adding another foot to the legth and height if possible...