Hi,
Is your overflow reservoir still full, and that is what you are going by? The radiator system needs to be "Leak free" in order for the shrinking radiator fluid to draw in water from the reservoir to the radiator top tank. So the water/air leak is letting in air, and not drawing fluid into the top tank. You will need to remove the radiator cap, and fill it there.
Radiator fluid is flammable. Yes - really. Dried, it can burn.
Anyway if you wash the area good, and clean the radiator fins for good measure, you should be OK to make the 230 mile drive. Lucky that it is the top tank, and normally it will not need to be full all the way.
I would check with
NapaOnline.com and see what a new radiator will cost. Most shops will not warranty a repair, and do not want to be on the 'hook' for a new engine if they make a 5 minute repair and it starts leaking again, and you do not notice it until the engine is bad. So they will get the price on a new radiator, add 25% - 50%, and then the cost of all the hoses. Add about 5 shop hours at $75 - $125 each hour, and give you that total. It would be much less expensive to do it yourself. If it takes you 8 - 10 hours, remember that the shop guy has no real shortcuts, and would be billing you 10 - 12 hours anyway, and you are saving $1,000 on this one repair!
I would be going home to make the repairs. If the RV gets to hot, pull off to the side, and DO not shut off the engine right away. Let it idle at about 1,200 RPM for about 2 minutes. Only if the radiator is empty, (IF temp is going up) then shut it off. But with the engine running, it is safe to add a little water to the radiator cap. After the engine has been off and cooling for about 10 minutes, with a dry rag (to not transfer heat to your hands) open the cap, and some steam will come out. Start the engine before adding cold water. Adding cold water to a hot engine can crack the block - a $5,500 repair. If the engine is running, it will not crack. If you where able to drive 100 miles between refills, stop after 90 miles the next time, sort of preventive time to add a little more water. Yet I think that you could make it all the way home.
Good luck!
Fred.