Lower weight rated wd hitch on a heavier trailer, unsafe?

If your tongue will spend the majority of its time over 1,000 lbs then get the 1,500 lbs bars. Blue Ox bars are built with quite a bit of flex in them. When you overload them, you cause them to over flex which permanently distorts the bar.

If your tongue is barely over 1,000 lbs, you still have to take dynamic load into account. This is the stress that the bars experience when going over road imperfections like dips. The bars experience quite a few more pounds of stress during such an event and that could leave them bent. That's why it's a safe bet to go one size up when you're close.

You might be better off with a new hitch anyway. You wouldn't get to take advantage of the lifetime warranty since it's only available to the original owner.