Teardrops n Tiny Travel Trailers

how do you bleed air out of hyd. surge brakes?

You can do it by pumping them. How depends on the coupler you have. If it's the one that the ball mount part kinda twists down and back a little, use a large cresent wrench on the nose and just push back, pump them up and have someone open the bleeder. Keep it up til you get good brakes.
You can also just open the furthest bleeded and let it gravity bleed for a while,close it and do the same with the other one. This is my prefered method but it doesn't always work.

any one know if surge brakes are legal on utility trailers in nevada?

i'd suggest opening the fitting on the brake and using a good quality oil can, pumping brake fluid in until it begins to show at the reservior on the master cylinder. I bleed light aircraft brakes like this all the time.

not to mention glider trailers. They weigh about the same as a big TD but can be 25 feet long or more

See if you can rent a brake bleeder from an auto parts store. The kind that you attach at the bleeder.

http://www.holeshot.com/old/ttools/brk_bldr.jpg