You may want to narrow you floorplan down first, and then consider the product line.
For example since you mentioned the Montana and Mt High country. These are Keystone products, both are wide units 100-102 width instead of 96". To further confuse this, Keystone also sells similar lines, also claimed to be "full time rigs" under the Avalanche and Alpine product lines.
Weights for similar models can vary by 3000 lbs or more. Water tank sizes can change some too.
Suggest you use a site like RV trader to get an idea of price variations and compare across the lines to see what lines have price and weights within the range your looking for. Some dealer also carry more than one of these lines making it easier to make direct comparasions.
An example
https://www.rv007.com/fifth-wheels
