HELP! Flashlight keeps dieing.

I bought a very nice LED Maglite with high lumins for the RV. It takes D batteries. Everytime I get the RV out of storage I have to replace the batteries. $$$ Sometimes it is only in storage for 2 weeks. The heat in the RV must be draining the batteries. Can someone suggest a flashlight that is LED, high lumin and can withstand the heat without killing the batteries?

Or a suggestion to solve my problem?