We went out today searching for a TT that will meet our needs. We were very upfront with every sales person that we encountered regarding only having 940 max tongue weight available and every one tried to sell us something way heavier than everyone on this site tells us is safe. We found one that we LOVED but then we looked and it was 5300 dry and the dry hitch weight was 800 frickin pounds. Even at camping world they were insistent that we could do 6000 pounds DRY WEIGHT! So so frustrating!
It seems to me the solution is simple. Get more vehicle or look at smaller trailers. Never use brochure weights, nor dry weights. If you use gross weights and then find you are actually a little under gross then you have a small weight cushion. Don't forget to include the hitch weight into your payload reduction. Use 75-100 pounds to estimate the hitch weight.
Most towing guides for vehicles provide the 'best case' for payload and towing. This usually is with minimal options, no other people in the seats, tools, dogs, bicycles, kayaks, bbq, chairs, etc. The more in the vehicle, the less the tongue can weigh to stay within the payload/towing guidelines. The receiver on your vehicle should be placarded with the maximum towing capacities. Typically
two values are provided. One for 'on the ball' towing and the second for using a weight distribution hitch.
Ford does an excellent job in their on line towing guidelines. For gas engines they prescribe a reduction in towing capacity of two percent for each 1000 feet elevation and also a reduction for frontal area of the travel trailer or fifth wheel. Their normally aspired gas vehicles operating above 5000 feet elevation and considering the frontal reduction the towing capacity for the vehicle can be reduced by ten or more percent. Diesels are not affected by elevation as they are turbocharged. Living in Oregon you will be in the mouuntains so elevations and grades are things to think about.
My suggestion is to get the towing/payload guide for your vehicle and use that when shopping. Then use gross weight, not dry, for the travel trailer you want and see if they are a good match. Then use 13 percent for the tongue weight plus the weight of the hitch. For example a fully loaded trailer at 6000 pounds gvwr will have a tongue weight estimate at 13 percent of almost 800 pounds plus 75-100 pounds for the hitch or a total of nearly 880 pounds.
The rule of thumb is to get the RV you want
first, then get the vehicle to tow it. Otherwise you are trying to find a RV to fit the tow vehicle, usually a compromise.