Looking good.
You must be very excited and happy at this stage
Couple thoughts on your previous questions.
Flooring. Definitely go with an all plastic hard floor. Especially for winter use. Use small carpettes in winter.
I used plastic planks and don't worry about water at all. Used a 1/2 inch solid plastic stone which is tough and durable as well. Costs more but I got it on sale. Besides, can install last and the actual exposed floor won't be allot so not that big an expense.
Tongue length
The minimum that you would require is 1/2 the width of the tow.
vehicle plus a bit. Allows for 90 degree turns without contacting. Can go longer by a few inches for more sharp turning clearance cushion if desired.
Necessary? If your angle is that sharp, what have you got yourself into?
With a trailer, forethought and skill come into play.
So what's the plan for roof attachment and sealing?
Did the same overbuild to 6x10 on a HF 4x8. Extended 1 foot on all sides. Points to consider, chassis and or floor flex effects and wheelwells. Light build helps allot with flex to a certain point. But not for enclosing the wheels. Had a flat once and a tire blowout can cause serious damage at speed. The original tires are only rated to 55mph if I remember correctly. Why many up size to a 13 inch tire. Those 12 inch originals are ok but consider changing if going to do any serious miles.
HF had to stop selling their trailers for a few years due to tire and DOT issues fyi.
On the road to Shambala...