So I've been looking to switch to a breeding rack and a maternity rack instead of breeding and maternity in 1 tub. I have seen a lot of people that use the mouse tubs from Freedom Breeder and ARS as maternity tubs but screw paying $8-$10.00 per tub. I know others also use litter pans but I came across Vision's new V-15 tubs 18" x 5" x 3.5" tall. Is this too small for a single mother with her pups or think it would be fine?