As you say we don't know exactly how big the snake is ... that said the wooden hide in the viv looks to be one of those pretty small ones ( not ideal anyway as the two openings offer very little security ) - suggesting that it's a youngster/ small Royal .. all that said - it could be an unusually huge wooden hide
From what I've heard recently there's virtually no difference in nutrition between mice / rats just more convenient to feed one rat than a couple of mice for the bigger snakes ..
PS - presuming there's another hide on the other side of the tank
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