a quick search on Google, gave me this webpage:
it shows a fictional "dry" weight of 5340lbs. add about 400lbs. for the normal "options" and you can figure it weighs around 5750lbs., before water, propane and cargo.
in fact, there's a '06 28A in Georgia, for sale and the dealer lists its actual weight at 5780lbs. so i was close.
the actual weight from the factory should be on a sticker, inside one of the cabinet doors inside the trailer.
and forget the owner's manual. none of FR's manuals are model-specific. they are generic and not worth the cost of paper it's printed on.
you'd be better off buying a RV book. and you can download most of the important manuals, for things like the fridge/freezer, a/c, oven, furnace, conveter, awning, and so on.