Richie, love the latest addition.
Soldering the bogie sides makes complete sense and your approach will ensure that nothing gets melted, that shouldn't get melted.
I didn't design the coupling bar to be bent over or be used in quite that fashion but hell, it works....really well!
Frankly, I'm amazed that you didn't have to cut out the V trusses for clearance, just be careful out there...
"Fiddlier than a fiddler at the fiddlers green festival", yup, that's a 1/8" 10BA cheesehead screw for yah.
Overall a super addition to resources to help construct the 42'. Nice one.