I was thinking the same thing.Personally, I'd go load range E vs a much heavier tire. Weight impacts acceleration, braking, and MPG whereas load range might make it ride rougher but keeping the PSI in the mid-30s should mitigate that somewhat.
MT Baja Boss AT is a D and 80# and the Toyo Open Country RT Trail is an E but only 75#. RT Trail is 3# lighter than my current KM3s that are a D and they are only 2# heavier than the AT3W that is a D. The only thing is the RT Trail has a tread depth of 17/32 compared to most 19/32.
I know I'm prob over thinking this but I'm buying 6 tires and it will be over 3k. Plus my KM3 have been on the road for 60k and over 3 years since I rotate 6. I will have them for awhile so don't want to get something I don't like and have to turn around and buy more sooner than I want too.