I have never been to any scales myself. But as a couple others I don't understand why some do not understand that you currently do not have a truck to tow with, seem quite obvious from your post. I look at max weight of trailer and tongue or pin weight and tow value and payload figures of the truck. If everything fits here, most all other numbers should fall in place.
I owned a 150 with a tow amount of 5700 pounds prior to towing. This limited me to a pop up or hybrid for the most pat. Upgraded to a 150 with a tow figure of 8600 and payload of 1700. With those numbers I bought a trailer with dry weight go 6000 and loaded at 7200. All was good but the trailer ended up not working for us so we upgraded to a trailer that was 6400/8000. I know this pushed our limits big time but this towed great, better than the previous trailer. After a year ungraded to a 350 SRW which can tow up to 12,000 and has a payload of over 3,800. All is real good now.
Good luck in finding something that works for you.