David,
Re the part of your questions and the actual weight of individual items, how bout going to some online stores, like CW and pull up the item in question, They have weights on there, right ????? So, what does CW say an A/C weighs, shipped, etc. Then, if you think the shipping weight includes the box/wrapping materials, then take off a bit for that.
My daddy use to say, you can have it all, but maybe not all at the same time!
I think most of us do that when we order our rigs, we decide which 'extras' are important to us, like we wanted slide toppers and are glad we have em. At this point we don't have a second A/C, and so far that has been ok, but we might add one if we go west for extended summer stays. Life is tradeoffs, even in the weight and the items we load into and onto our Montana's when we venture out of the yard.
Some of this has been a bit techy for ole Carol, but Al is reading with interest.
Carol