We have a truck with a problem, and you have to drive 1,200 miles towing a small trailer, is that right?
Oil in the coolant can't be good. You just put in a new radiator, what will the oil do to that? Can you reschedule your trip? Rent another vehicle? Get the gasket repaired at a shop where you are, rather than drive it home and fix it after 1,200 miles? You are taking chances that what's left of the gasket will hold up and won't blow more coolant out during your trip. If the motor overheats it can cause more significant damage, more $$$ to fix.
What's more important your trip or protecting the investment in your truck?