I don't think you're being silly saving 32lbs. of unsprung weight. It's a pretty significant amount and I know some enthusiasts that sweat ounces when it comes to wheel and tire choices. If you drove your vehicle back to back with both sets of tires on you would definitely notice the difference.

I can't speak on behalf of BFGoodrich, but I can surmise that like most large manufacturers, they err on the side of caution when rating a tire, and more than likely that rating is good for the life of the tire, so as long as you're not driving over 100 on 10 year old bald tires they will probably not shred on you. But I've seen stranger things happen to seemingly good tires.

If you are indeed limiting yourself to light off-roading, and to me that means gravel roads, fire roads, and maybe a small rock or two on your trip, then any KO2 tire will suit you just fine. I run a lot of trails where if you take a bad line, you have a really good chance of getting your spare out, and so I run E rated (KO2's for 30K miles and Cooper SST Pro for 6K miles) for the extra sidewall and tread. That being said, I also run these same trails with a buddy that runs C rated Nitto Ridge Grapplers and hasn't had a flat yet either, so..............