If you disable everything, it shouldn't be a problem.
And a more general question: are there any custom campaigns in Heroes of Might and Magic 5 that are similar to those in Heroes of Might and Magic 3, consisting of multiple multiplayer maps (not scripted) with various victory conditions (not just "defeat all") and a text-based storyline? Because such campaigns would be ideal for playing with the Ultra EE mod (in EWA/MMH5.5/with a clean installation).