I'm always messing with different bulbs and my current 6K & 10K setup is something I have only had put in for maybe a month. Before that, it was 6K & 6K but I do agree with the digital slim ballast. You can get two kits, one 9006 and one 9005 because the highs really don't take that long to warm up. It's not instant but for me, I'm looking at maybe 4 seconds and after that, if you have to shut them off because of oncoming traffic, they'll strike right back on without any warm up at all. Instant! I have done this many many times and have yet to blow one bulb.
Now, you being out in the country and without street lights, I would either go with 5K or 6K. The 5K should be very white as mine are 6K and are very white with a very slight hint of blue but I see more white than anything. 8K out in the country would be ok but not super bright like you seem to be wanting. I do have pics below of 6K, 8K, 12K and dual 6K's & 8K's. I have had 10K in my lows before and they are blue with slight white but I have no pics of them on hand.
6000K Low beam only
8000K low beam only (sold to another member on here)
12,000K is just plain stupid but I tried them anyway. If you end up going with 12K, go ahead and buy two fart can mufflers for it too.
This is 6K and I believe 8K highs and lows at the same time. 8K were in the lows. Keep in mind, most of this light was coming from the 6K highs.
This is the 10K color coming at you, low beams only.
In the sig pic below, that is 6K with a relay kit installed. Just like mentioned above, everyone has their opinion and we have our likes and dislikes. I didn't go with 4300K because that's basically factory. I like "different" and wanted that touch of blue. All bulbs above you see, were tested in brand new out of the box housings and not all were aimed dead on but were aimed good enough because of testing. I really wouldn't advise the 8K for the country. 5K or 6K would be my choice. Again, it would take many re-strikes of the highs to blow a bulb as I have just sit and done it over and over and didn't care if it did blow a bulb and I never blew one. They say it's not good for them but going down the road and only re-striking long enough for the oncoming car to get by you, you're not hurting them. I have more than tested that theory.