Kitz,

You got a good point there.
Trailer and car are dead level in static position.
I did a little test and hung 250# on the hitch and measured < 1/4" deflection from the front frame beam. Tongue weight should be around 50-75# fully loaded. trailer empty wieghs 195#, which gives me 500#+ for load capacity. I am using .187 wall 1 3/4" MS tubing for the tongue and 2 x 2 x .120 for the main frame. tongue goes through the front frame member and welds to the rear frame member. It certainly couldn't hurt to add some lateral braces all the way to the hitch to make it a full "y".
John