Trim that curves from "hitch" area down in front of landing legs separates about 1/4" from siding when hitched to truck. Just around curve - 12"? Gap closes as weight shifts to legs when setting up....
Don't remember reading anything about Sunnybrooks having frame issues but the symptoms are not good! You need to open up the bulkhead area around the pinbox and have a look see! Good luck with this!