This is my take on it:

Start them in pairs at 10 second intervals.  This should increase the time it takes the leading guys to catch the later starters.  If it's safe to start them in pairs for practice, which they still do, then surely it's safe for a race too.  Particularly if it lengthens the gap between number 1 and number 90.

I would also revert to the old numbering system.  I've never heard a convincing argument that there was anything unsafe or impractical about it.  Wasn't broke and didn't need fixing.

I would also abandon the concept of a top seeded rider carrying the same number throughout all solo races as they do now.  This would serve to change the dynamic of a race and make the whole thing more interesting and unpredictable if they started at different numbers in different races.  Three times within the last few years we've seen one rider domninate throughout race week and I believe this will happen more often if things stay the way they are.