About 20 years ago a major RV manufacturer (who I won't name) designed an all new gasoline rear-engine 32' motor home but kept the radiator in the front. Despite consultants, boost pumps, larger pipes, etc, they kept having problems with the large V8 overheating and blowing. After shipping about 30 vehicles they recalled all of them, refunded the money, and scrapped the vehicles and the entire model line (allegedly due to a brake issue). Million$ of dollar$ of engineering, tooling, and product written off and I know they were still having overheating problems. Apparently even with rear engine busses, there is a reason the radiator is kept in the rear.
If your genset supplier is hesitant to remote the radiator, you might want to listen.