Let me get this straight, you are asking if you should get KDSS on an admittedly hard to come by trail, so that you can "maybe" take it off the road once a year? And further more, it's because there is not much to do off road in Minnesota?
One... I know some that would love to differ with you on the later part.
Two... Do you need a sniper rifle at the pistol range? Really, it's like the soccer moms down here who buy land rovers so they can maybe see the grass at the soccer field. I know the trail is cool, but unless you want to seek out new and cool places, rock crawling, or serious offroading, save your money. (and save the trail for those that would put it to the test)
Three... KDSS is realitively new. Yet you see what people are doing in their 4runners and FJ's pre KDSS. My previous stock 05 4runner ran through some muddy ruts so deep my left wheels were off the ground because the center rut was bottomed out and I was leaning on the right wheels. The 4runner did not even think about getting stuck. (made me want a lift though)
I've been in sand so deep in my new SR5 I was plowing it with my skid plate. Still, not even thought that I was even close to getting stuck. (Again, lift is coming soon)
Some of the dumb stuff my son has done in his 97 limited 2 wheel drive 4runner has me wonder how many people will ever need their 4x4. I'm sure he has a thread here somewhere with pics.
So to answer your question. Do I regret not getting KDSS? Yes, because I wanted a trail so I can crawl, do some mudding, and really run the hell out of it.
Given I could not find a trail, I got another SR5 and am totally pleased with it, and it's capabilities. (Surprised actually)
Once a year wheeling, you probably will not gain enough knowledge/skill to miss it.
I know the TE is a bad mamma jamma, and I certainly understand the lust, but you, could save your money and be totally happy without KDSS, or a trail for that manor. If you must have a trail, get KDSS, that way you'll never have to wonder if you'll miss it.
As for your second ballpark an addition... without having an idea what you'd want to add, how could one ballpark that?