I couldn't find a way to do it before so I tried to do it myself. I succeeded, but I do agree that this seems pointless now, since the other way is easier.
to hackmew: editing the tiles wouldn't do much because its four tiles that are only used in that map. In the script we are editing, we don't even know what it does since it has only the cmda6 command. You don't have to use this map either. You could create a new one and use it as the starting point with your SMCA and warp to the truck, if you so desire. But I'm under the impression that if people want to have the truck effects off also means they don't want the truck either.
Also, you probably used the transparent color instead of black. For info on that, look at the Tutorial video I made in the original post.