Just get Xavion
Tom,
I bought a new Mini Ipad to try Xavion thinking I would need a SAGE or LEVIL AHRS, however I was wrong.
The synthetic vision and stand alone GPS function is nothing less than amazing.
In a bubble top like an RV or Rocket the pitch, roll and flight data is smooth and fluid - better than some of the dedicated EFIS offerings. No external feeds required. The hits and waypoint insertion/deletion is quite useful.
In the back seat it would be just like having a HUD for your passenger in the place of the back of your head. It works best when mounted vertical and square right in front of the viewer.
Linking it to your AFS would be icing but your wife in the back seat could fly x-c and take you to short final with Xavion alone.