The reason we advise to disregard the dry weight is due to the fact that first, it will only be dry when going from the dealership to your home and secondly, many dry weights do not take into consideration many of the mfg and/or dealership's options/accessories. These can include many of the things that you would think would be taken into consideration when they come up with the dry weight....but do not. Batteries, propane (and tanks), awnings, televisions, and yes sometimes even microwaves, refrigerators, furnace, ACs, larger beds, etc. The "actual" dry way may be hundreds of pound more than what they advertise.
Another factor to think about is that many people will estimate the weight of things they will put into a truck/trailer.....and be way under the actual weight. That is why we recommend getting the vehicles weighed on a scale. Let's face it....estimating is just guessing.
Many of us here on rv.net like to recommend the 80% rule...that is, to never exceed 80% ANY of the vehicles ratings. This provides a very good safety margin for both you and the vehicles.
Good luck in whatever you decide.
Ron