Similar to what I'm doing.

For H1, I create a matching B1 for body text for that level, and format the H1 to have B1 as the following paragraph format.

Still working out the kinks, as I'll need to create additional formatted styles (bullets, notes, etc) for each heading level.

Don't think I'll be able to use the add-ins at work (defense contractor, so high security levels on work computers, but I'll play with it at home.