Cutting hole in house big enough for small rat but not a larger one

[Kaat]

I am going on vacation. I cant have someone come to my house to pet sit so the rats(x2) have to go to a friend while im away(about 4 days). I obv can not bring my critter nation to my friends house so I have a kaytee brand travel cage large enough for a hammock, a wheel, and a house. My bigger rat(400g) sometimes picks on the smaller(250g). Never aggressive, and never injury, just dominant badgering like "oh your in the hammock well not anymore! Now its mine!" Any the smaller is just like "ok" and goes to a different hammock. Dont get me wrong I find them snuggling all the time, its just that the larger likes to throw his weight sometimes. With a smaller cage im affraid the badger may escalate if smaller has no where to go. So I want to cut a hole in a house small enough for mr smalls to squeeze into but too small for mr bigs to go in. I have no idea how to measure on a rat for that kind of thing and have limited material for trial and error. Should I measure shoulders? I fig if they can get shoulders in then they can get the rest in, or is that too wide, should I measure just a little bigger than their head?

 

[SQ]

I would be concerned about that too ….

If they can get their head through a hole, they can usually get their body through ,,,,, so cut a small hole and use trial and error to increase the size of the hole
But, "the badger" will likely just chew a large hole in the house if he wants in

Is it possible to put 2 hammocks, 2 water dishes, and 2 food dishes in the cage on different levels?
I am assuming a cage large enough for them to stay in for 4 days would be large enough for 2 of these items …… even if the hammocks need to be hung one over the other with some vertical space between the two

If you have enough time, and your friend has the space, you might want to consider getting a martins powder coated rat play pen (martinscages.com) - which is a good size when set up but folds for easy storage (I have the large one)

 

[jorats]

I definitely would not make a hole for just the one rat, the other will try desperately to go in and could get stuck. But, I know i'm late to the thread...just the fact of moving houses and going to a temporarily small cage could make the two rats bond together.