I'd suggest using those garages you can get from places like Carrefour:
https://www.carrefouruae.com/webstore/Product.aspx?productid=8743&ref=bkam.com
Then add a heater to it and try putting the garage on his old burrow... I think that would work well, it costs money. Here it'll cost $2150, without heating :/ think it'll work?
Edit: maybe you can cover the door to that garage, and make it fit your Tank... Less water will go in, hope I was helpful
https://www.carrefouruae.com/webstore/Product.aspx?productid=8743&ref=bkam.com
Then add a heater to it and try putting the garage on his old burrow... I think that would work well, it costs money. Here it'll cost $2150, without heating :/ think it'll work?
Edit: maybe you can cover the door to that garage, and make it fit your Tank... Less water will go in, hope I was helpful