Rear-facing child seat position is required for a baby that young.
Frankly, since the only true passenger-protected area in a Class A is the cockpit and you want the baby to be as safe as possible, the baby's seat should occupy the copilot position. Airbags off if possible, but not so critical with a rear facing child seat.
" Not every mind that wanders is lost. " With apologies to J.R.R. Tolkien