How to play fallout new vegas after ending?

I just beat fallout new vegas' main story line and I'm pretty pissed that I can't continue. I don't give a **** about everyone saying "well the ending is final" I want to beat all the side quests etc. and I also have bought DLC that I can't ******* play now. If none of the people in the game refer to what happened at the hoover dam I just want to play the game longer. so if there are any solutions that do not involve having a save file from before starting the hoover dam quest. I'm on xbox 360 if it changes anything.