I do all my drives with offroad+ and gear in D. I switch in and out of manual mode depending on the terrain - if we're going into an area that will call for many climbs in a row or continuous climbing, I swap to manual so I have the required power on hand by shifting down a gear as needed. Most of the time I'll use 2nd gear with 1st gear reserved for steep climbs with small run ups. Losing power by hitting rev limiter on 2nd gear is pretty rare and I think it happens more because I lose traction and the wheels just spin, in these cases I shift up to 3rd and the lower torque helps to grip the sand better and then I shift back down to 2nd if I still need power
There are some who say staying in manual all the time is better but I've found for me at least a mix works and probably puts less strain on the engine. I find Offroad+ quite good and 90% of the time it is in the right gear for the job.
Oh and always 4H part time for me. On the 392 at least it is bad for TC to drive on loose surfaces in 4H Auto