Here's the link to U-Pol -
U-POL :: They have Dolphin Glaze, which is a self leveling, pourable/brushable; and also Dolphin Putty for vertical surfaces. Like any filler product the working time is somewhat controlled by the amount of catalyst you add, but this stuff is advertised to be solvent resistent, ready to prime/paint in 15 to 20 minutes. You've got four or five minutes to work before it starts getting stiff, and of course better with ambient above 60/65F.
This is just the stuff that my paint supplier sells, and since he's been doing custom painting for about 40 years I listen to him when he takes time to walk me through the process. He tends to find the best products for the money, mostly suppliers that don't spend millions on advertising.
Found a new recipe for Beer Battered Fish That's GREAT!! - -
the Official CHR joke page duel