Why do people think the England post requires a full-time manager at this time? You see shared duties routinely happening in North America with their national basketball and ice hockey national team programs. By and large, it works very well and this approach offers England the best overall, short-term solution.
A manager like Harry who's already running a top Premiership side is completely current to the game at many levels. He probably hears, sees and schemes about more things than some ivory tower-appointed interloper. Let Harry have the post with Pearce or some other assistant attending to the minor administrative details. The team will practically pick itself.
Only issue would be how much the strain of the trial has affected Harry's appetite for action.
If the FA were looking for a slightly longer-term solution, I'd be chasing Mourinho. Ideal holding-pond post while he awaits the retirement of Sir Alex.