That's slower than most areas around my end of the world allow; there are some slow sections, for sure, but you can usually run between 35 and 55 even through the loose stuff around here, naturally slowing for ruts and ditches and debris and places you can't see clearly, and what-not. I'd still say to leave your pressures at a comfortable street level until you need to air down, but if you're on 35's and you have beadlocks and a tank, you can try it any way you like.
Without knowing much more, I'd say you could run as fast as you like on the way to the trails; my point regarding specialized vehicles was that I don't see that many rigs going more than a couple of miles per hour when they hit the parts of a trail - not a service road - that actually require airing down, and that I also don't see the point in blanket "air down and disconnect" advice for terrain that doesn't need it.
Let me try to say this another way: my advice is to avoid doing things that you don't need to do, or that don't help. If you get somewhere and say "yeah, I need a little more tire deformation here" then lose some air. If you need to disconnect, fine: disconnect. If you don't need to do those things, then don't.
