Does the trailer leak?
Not that we are aware of - ie the roof does not leak. The back doors (where you would load a horse in originally) have rubber strips that need to be replaced from time to time or water will get in that way
Any electrical wiring for lights needing repair?
Not that I am aware of - however it has been sitting for a few years.
Does the hitch need to be replaced?
The length of 11 ft - does that include the tongue/hitch or no?
11' include the tongue/hitch
What are the interior measurements and dimensions?
The walls are only 1/2 - 2 inches depending on if there is a panel or just metal, so you could subtract 1- 4 inches.
Would it be reasonably easy to replace the sofa with a pullout bed?