Given how many ranking personnel from the armed forces and Abwehr were employed by the FRG, I'd imagine Rommel gets some sort of advisory position. BW will have a better idea of what Rommel might be offered and accept though.
I doubt he would return to active duty. For one thing, he'd have to go down a rank since the Bundeswehr only goes up to general. However, the Bundeswehr has plenty of civilian positions, and the Rommel myth was powerful stuff. If he decides to play along - and he was a careerist with an eye on the main chance - he could well become a very senior official. He's probably too controversial for Wehrbeauftragter or Staatssekrtetär im Verteidigungsministerium, but I'm sure they'd fund a desk for him in the Hauptabteilung Rüstung. Everybody would call him Generalfeldmarschall anyway.
(A friend of the family entered the civil service in the early 50s. An entire department of the revenue office was staffed by ex-navy guys, mnost of them from the same u-boat crew, and whenever the department head gave instruction, they'd click their heels and go "Jawohl, Herr Kapitänleutnant!". Early West Germany was weird.)