When I bought Dawnguard I had completed almost every quest in the game. My guy was level 38 and because I was running 45+ mods my game crashed and I couldn't save the save. So this time I removed all mods beforehand and did 3 clean saves. I sure dont want to have to start over again!

I'm not worried. Dragonborn doesn't add much into the main world space so I don't see much room for conflict. Besides, I'm going to run the .esm through TES5edit to remove any dirty edits.

Eek! There is no such thing as a "clean save" in Skyrim. Uninstalling any mod (but particularly those with scripts) and continuing with an existing save game is not recommended by Bethesda and is not supported - you are more likely to have crashes if you remove a mod than if you leave it active - and reinstalling the mod later won't fix it. Data and script references get embedded in your save game, and when you remove a mod and continue the same save game, you will run into issues at some point.

If you want to remove any mod, it is recommended that you start a new character after doing so.