Two ways I see:
Write function that wraps polyfit and only returns the slope instead of using anonymous function. Presuming the above code is already in an m-file script or function this wouldn't be too bad to make a local function within existing file.
Alternatively, just fix up the existing table/timetable -- I happened to have a table already in workspace so
Just write over the original table with the retrieved slopes array. The end result of above here was:
Fun_P1 Fun_P2 Fun_V Fun_S
______ _______ _____ _______
10 0.59253 1.315 0.11128
With your timetable, use it instead of course. Not sure what you did about the time; don't recall what varfun does with the time in a timetable by default, actually...