Having towed hundreds of thousands of miles and maintained many trailers from my own to fleet trailers, pretty much any grease you pul off the parts store shelf and put in the gun that is high temp, synthetic and or lithium will work the same.
I use mostly Lucas Red n Tacky but it's really not that important. What's important is making sure the bearings are greased and the seals not blown out. My last Snomachine trailer had an est 40k mi on it. Pulled the bearings for the first time before heading to AK last year and was gonna replace them. After cleaning them up and checkin them out, put em right back in and drove pretty much non stop to AK from WA with the trailer overloaded. Wheels run cool.
Just give me a few squirts of grease every couple thousand miles maybe more if you're hauling real heavy.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5โ turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold