One route to go on getting curved stems installed:
I got mine here:
https://www.shinyrv.com/product/dually-valve-stems-for-motorhomes-with-alcoa-wheels-2-hand-hole-dl4ac/ If you call them at 714-642-3646 they will know the exact curvature you need etc and will ship them to your door. You may save a few bucks shopping around but this was sure handy for me. The hardware I got included the rubber inserts to stabilize the longer stem so no worry with installing a tire pressure monitor sensor at that location.
As enblethen posted, any truck tire shop will install them. I used Les Schwab............. about $85 IIRC.
One of the downsides: The inside dual will have a valve stem that is too long for spin balancing. I just installed Centramatics on the rears but you could have the tire shop use beads.
Good luck with the upgrade...... and save travels to ya.
You will be very happy with the results.