I suggest backing up just a bit and analyzing your usage and your definition of off road driving. Some people want to race at Baja and want super long range lights. Some of us crawl through brush-choked and washed out old logging roads in the soggy Pacific Northwest. For me, it's not so much long range, as seeing around switchbacks and into holes that appear in front of me, as well as seeing to the sides and rear when I need to back up and turn around. I like your plan to mount lights near your bumper ends, angled outward to the sides.
For me, reasonably good halogen headlights, plus a big set of old Cibie clear fog lights (so the lenses are sandblasted and the reflectors beginning to degrade; they still help me see to the sides and the increased "scatter" from the blasted lenses is not a bad thing), handle most of the forward work. High mounted spotlights with landing light bulbs, can take care of special needs.
The rear has two sealed beams inside the 6" channel bumper, and two sealed beam floods mounted high on the sides of the bed. The lower rears are the "sealed beam fog" pattern. The uppers are flood lights.
If I was planning more off road work with that truck, I'd add side floods. But the spots can handle it for occasional use.
I did add a flood capable of being angled downward, to the top of the front end guard on the extended bumper. This was after I got a deer on very steep terrain, and the very end of legal shooting light, and it went over a steep bank before it piled up. I got the truck crosswise of the road and we managed to let the winch line down over the bank, then found that none of my lights could help me. The powerful high mounted spotlights at the top corners of the windshield were too far back to be able to put light down over the bank. And my rechargeable flashlight ran down... That PAR46 flood came in handy many times after that. It had enough "scatter" to be useful operating the PTO winch, and it filled in the area right in front of the truck, no matter how steeply I was looking down.
For slow speed off road, it's not super high light output or long range. Oh, I had a Marchal 902 pencil beam on the front end guard, too. But that was so I could see down the highway at speed. It's coverage everywhere that matters off the road.
Also, my experience with infrequently used trucks that sit outside in a wet climate, points me toward sealed beams, regardless of efficiency. If it's a sealed glass lamp, the reflector won't "go away," as even some Cibie lights have done. The lenses won't fog up. The fixtures won't fill with dust and dirt. Look into those housings Scheinwerfermann suggested, then look at the available selection of 12 volt halogen sealed beams in that size.
What I have described works for me. If your kind of off road driving is running at high speed in a straight line of flat ground, ignore everything I said, and start looking for pencil beams and spotlights.
