Might be tough to look under the laminate floor. perhaps an ice pick around the edges. Poke it, if the pick goes thru, might be rot.
If the sink supply lines were the origin of the leak, and you had not noticed a leak on earlier trips, my guess is probably no rot issues. It' s a good idea to check all the sink supply lines regulary, they can and will loosen from bouncing during travel.
The carpet inside the cabinet is likely original, just cut/pull it out or back and take a look. If it was wet the pad underneath will be difficult to dry out and will smell yucky.
The toilet would be a seperate item to check. It may have rot around it, may not. Just depends on the PO and how well they maintained things. It is not difficult to pull up, just be sure to replace the rubber seal. They are cheap, so buy a couple to have on hand.
Many folks put laminate flooring in their trailers. Some get tired of dirty carpet, others put it in to cover over rot or other issues.
I'm bettin' you are in good shape. You really would not have to wait till spring to take a look, you won't need any water, just maybe some heat to keep you comfortable while you work.
Region 3 , 1st VP
Go often to the house of a friend, for weeds choke the unused path........Emerson
Never pick a fight with an old man. If he is too old to fight he will just kill you........a wise old man.