However...
You still need to weld on CLEAN metal; grind/disc/wipe all paint/primer off prior to welding. I know Don knows all this. I'm very new to welding auto-body ('pretty' stuff), but I used the weld-thrus for a long time & yes, you can weld through it...Depending on the gauge of the trailer steel, you will also need to crank the welder up with these primers...
The epoxy primer Tim suggests is the best primer I have used. It is also the hardest thing to get off when cleaning, prior to welding. That is a good thing.
I can't defend all this with 'I have xx years of experience', and an untold amount of variables are out there, but you need to do any & all metal welding on the absolute cleanest metal possible. Why not have the best primer coating possible? (if you do have to clean something off)
Brad
