GM Guy,
Let me do this in reverse order, because it makes more sense.
1) Your 35 psi rated tire - can be inflated to 44 psi, so from my perspective 38 is OK.
There's a part of the tire standard that says the load curve ends at 35 psi, but there are certain circumstances where higher inflation pressures are called for - high speed operation is one of them. But the law that applies to what is written on the sidewall is not quite clear which of these 2 figures is right and different tire manufacturers do different things - even though the standard is the same! So the same size tire could have either of these values and there's no difference in the tire - just the way the law is interpreted.
2) Vans? Unfortunately steering like a pig is what vans do! Sow's ear / silk purse comes to mind! So long as you don't exceed the max on the sidewall it's OK (for LT metric tires)
For some reason, even though the same standardization rules apply to LT metric tires, everyone seems to agree about what gets put on the sidewall - the pressure at the end of the load curve. I'll have to look again to see if the law reads the same (It's a different regulation!)
3) But when it comes to P metric tires, if 44 psi (or 51) is written on the sidewall, I'd be careful using the tire at that pressure. (Read #1 above.) While steering response gets quicker as you increase inflation pressure, impact resistance goes down. Just use caution!