Don’t think Ram specifies any mileage for towing with the TRX. But I tend to wait at least until 1000 with all my trucks. By that point I have changed engine, diffs and transfer case oil and everything is good to go.
The engine break-in recommendations suggest no towing or high speed off-road driving for the first 1,500 miles. I doubt many people follow that though, the off-road part especially.