Some of the new {aerosol}formulas don't like being sprayed on too thick..You might get it built up to match the surrounding areas only to find it cracked while drying or shrank and needs another coat anyhow...Take your time and don't rush it if you go that route...

The old style undercoating had it's own spray gun that screwed on top of the container and splattered up everything including the floor..The discharge hole in that gun was almost as big as the air hose diameter itself...So you won't be running any thick undercoating through an HVLP paint gun no matter who's formula it is...

As stated cover everything including the floor it's going everywhere even if you use an aerosol can type product... I wear a disposable suit and old shoes.. there's no gracefull way to do it !!