Welcome to the Jayco forums, and looks like a clean install on your mods. I once considered mounting a storage box similar to yours on my TT tongue, but the weight became an issue with my set-up (I also have two 6V GC-2 batteries up there).
Do you have any pics showing the tube frame attached to the TT frame, I'm sure others would be interested as well.
2016 GM 2500HD 6.0L/4.10
2005 Jayco Eagle 278FBS
Reese HP Dual Cam
Putnam Class V