Chasis A/C condenser - blocking air lfow to radiator?

A couple of possibilities you might try. You might check on the addition of an electric 12V fan, push or pull, in front of or behind the radiator and thermostatically controlled. They have been used on some motorhomes and cars and trucks also. Another thought might be to try shifting down one gear and let the engine rev a little higher up the hills to work a little easier. Hope this may help, Happy trails, Bert