Is it safe to bridge

I did a search and found two threads about builds where people have done this, so i am assuming it's safe but wanted to double check. Putting in a 30amp 2 pole breaker with a 30amp rv cord in a 7x14 cargo trailer. RV cord only has 3 wires(neutral, hot, ground), breaker box has 4 post, (2 hots, neutral bar and ground bar). Is it safe to run the one hot wire into one side and make a bridge wire to get power to the other side? I have two 15 amp breakers. One for dedicated AC unit 1200btu/12amp and the other will run two lights and a couple of outlets for generic use. I will use regular 110 house plugs, 30 amp campground plugs and also a 3400watt generator for power. No DC current at this time. Going for simplicity and with the the generator didn't see the need for DV.