GPW the 2 ½” X 2 ½” X1/4” angle stock will work just fine for the frame and the cross bracing. For the tong you will need seg-40 or 80 black iron pipe. Seg-80 would be better. And put in V bracing for cross stress in the tong. As long as the welds are good the frame will be strong enough for a 2000 lb trailer. Which is a heavy weight tear. Good luck on your tear!
I have seen utility trailers made of ¼” angle iron that was bolted together with 8 point screws that have over 100k miles on them.
Chuck