Rough Opening for Door

[cabinboy]

Building a small cabin and new to this so here is a basic question. I am planning on using 2x12 material for header above pre-hung door and since it is only 11.25 inches wide, my rough opening will be about 82.875" rather than the 82". That is 92 and 5/8 stud less the 11.25 for the header, plus the 1.5 for the bottom plate where it is cut out. Will this be OK? Or do I need to put short cripple studs above the header or maybe some 1x material?

Thanks

[Rich]

I would keep the header tight to the top plates. The space between the top of the door jamb and your header can either be furred down with 1/2" material (plywood) and filled with insulation or simply filled with insulation.