Are there any counter indications to loading all 5 DLC packages at the start of a game? Such as map conflicts or resource hogging or general confusion?
Nope,actually it is better to load all possible mods and DLCs and start the new game than adding them at different times or loading previous games.
Bugs and textures and so will be overwriten or constant rather than making sudden changes in your savegames which can lead to missing file/texture for other mods...which will cause avalanche of crashes.
Note: DLCs are official and are bug tested(mostly),adding many mods(community) will make serious problems as gametime goes on.