Since we're talking offroad, it doesn't have to be a highway legal headlight or driving light.
My 2000 Crown Vic is a former cop car. The spotlights use the H7680X bulb. That uses HIR technology, to give more light output from 80 watts than the traditional (or used to be a traditional "upgrade" in the past) #4537 100 watt landing light, yet it has a 300 hour life, as opposed to 25 for the landing light. For a "quick fix," you might try a pair of the H7680X bulbs, taking you from 300 watts drain to 160 watts, and giving a nice long life. There's also the H7680 bulb: it has a bit more output than the H7680X (275K cp vs 230K cp), costs more and has a much shorter life.
A source:
http://www.replacementlightbulbs.com/lamph7680x.html
Not long ago, at work, I replaced the bad bulb on a Q-Beam handheld spot with the H7680X bulb. It does have a convex face, but that was no problem. Brinkmann wanted more for the short-lived Q-Beam bulb, and the H7680X made better light for less power drain. We sometimes use these lights with a portable battery, so I appreciated the efficiency.
I live in wet country, and my vehicles usually sit outside. Therefore, I appreciate real glass sealed beams, particularly on trucks that sit a lot and only get used offroad now and then.