This gets a little tricky. Keep driving it and check back with how it progresses. I am guessing that the FSS will extend it out more than this, but not right away, or maybe not by actually "increasing" miles, but by retaining them. In other words, right now, it looks like it'll be due at 11,000 (7000 miles on it now, plus the 4000 that it says it'll be due), but it actually is going to "hold on" to that 4000 mile figure for awhile now (not start taking miles off right away. Keep an eye on it. I think it only goes in 100 mile increments, so drive it 100 or so miles and tell me if it then reads 3900 miles or not.
ps I think what you are doing with your truck is fine, I don't try to force my views onto other people. I try to be a good German and follow the company line, so to speak. Or at least try understanding why they do what they do. But no dipstick? Geez.
I do think it is wiser to get a good long use out of your oil, better for our non-renewable resources to use the "new" oil as long as possible without causing engine damage.