Nice job on that DogHouse!!  I especially liked how you designed the bike rack, simple yet effective!  I would encourage Dad to re-weight the TT once the back os packed to be sure he still has enough tongue weight, otherwise it'll sway like a bee-otch.
I would also consider adding some lighting to the back of the rack if possible.  The rack sticks out pretty far and the bike helps to obscure the factory lights.
I moved the factory bumper back and added extra lights:
