Some manufacturers recommend against it, others say it's OK. Keep an eye on fasteners obviously, and as you said drop tire pressure to like 15psi.
My only experience towing one empty was a Uhaul dolly for ~100 miles. Holy **** was that loud! Like embarrassing, people looking at what is making all that racket loud. I'm pretty sure the tires were in the air as much as they were on the ground... Didn't drop tire pressure though since it was just an emergency rental.
If I were going 1500 miles with one, I think I'd toss a few bags of concrete on it.