You are getting there and finding out what works as you go, thats what its all about. If you need more cooling, you could always add a second small radiator under the bed with an electric fan, it would add capacity and some cooling and could be plumbed off the heater hoses, it might need and separate pump to move the water along. Even a heater core down in the wind would help.
I know my 250 is hotter at the back of the engine and at the head compared to the block and radiator, so it may not even be a problem as long as it doesn't puke all over the driveway when hot.
