Sure does look like crap as you say.
But I will rescue you.
First remove the white crap as you call it.
If you are good with thinner base products it will be easy to remove.
Wipe with thinner base fast and swift motions to prevent meltage of the plastic.
Always have a wet rag to follow to...
As an individual in aero studies air flow will sound when spaces permit wind / air in this sense to flow disturbed.
Therefore, try to fill the gap with minimal cost - solution - purchase from Home Depot or the likes a roll of styrofoam
used in covering hot water pipes that are out in the...