Preventing condensation-standing seam metal roof over metal MH roof

I am contracting for a standing seam non-vented roof over for an older 16x76 mobile home (with an existing thin-layered metal roof with a slight pitch). Planning for 1-inch rigid foam foil-covered (both sides) insulation, and using synthetic underlayment. Location in South Central Texas. Cathedral ceilings in 2/3 of home, tiny attic space in other part. Please advise about whether AIR SPACE is necessary, and if so whether it should be above or below the foam board. Should it be: Synthetic underlayment, foam board, 1 x 4 lathes (3/4 space between ends?), then unvented standing seam roof? THANK you in advance ... they're hoping to start midweek this week.

You can skip the foil faced foam unless you were designed it as a radiant barrier application.

Should be fine. Put the foam down, seal and detail out the seams, and an air space is NOT necessary if you get all the closures and details sealed up