I'm surprised noone appears to have noticed this, but the game has like 64 4th division groups active when there isn't even a full Div3, yet alone many teams. As such I'd recommend:
Get rid of Division 4, which also means no relegation from Div3. If possible, expand the number of teams that can be in each Div3 group, most Div3 teams aren't active anyway, or if not possible, then have more Div3 groups.
Alternative in neither of the above is possible, then have Div4 teams fill a single Div4 group at a time, so at least they might get a chance to race against somebody.