What I could do is get around a 6qt anyway and try to feed him the live prey in it later this week. He's seemed to stop wiggling around during the day time lately, especially that I concealed all sides of the tank, and has taken to just chilling in a hide or coming out for a short time to drink and bask. If he still seems disinterested after a try or maybe two (however long I need to stall to gather funds to set up a tub), I could then use the tub for his enclosure until he gets another 100 or so grams on him and is eating regularly and keep him in bigger ones until he's big enough and eating regularly enough to move him into the tank. It would make sense since he was raised in a tub anyway.
Unless it seems really unlikely he will take the live, I'd like to avoid getting stuck with a mouse to keep alive until he wants to eat especially since it'll outgrow his food size. In your experience would you say the tub is more likely a solution? I can get most the supplies to set it up tonight.