How do you know you're towing too much weight?

My head is spinning. Sticker this, pro and con, and payload-axle-tongue that, and brakes, and construction. Maybe we should have gone back to a small Class A! Thanks to everyone who "weighed" in.

We brought our new TT home yesterday, and will load it up and get it weighed tomorrow. I intend to have it no higher than 6000#, give or take 100#. If it's too heavy, out goes the coffee-pot.