Welcome to the forums!
Nice looking rig! It may well be a Komfort and just had the Coleman badgeing slapped on it. Coleman doesn't build anything anymore it is strictly a licensed name now.
I doubt you will find any frame drawings for your unit, you will need to find the rafters yourself. Several ways to go about it, one is to pull the interior garnish on an existing vent, that will let you see what the construction is and might give you an idea of the rafter spacing. You can look for ceiling fasteners and see if you can establish a pattern.