You can simply adjust your batch size to 5.25 and enter the O.G. you measured. Keep adjusting the brewhouse efficiency until the estimated O.G. matches the one you entered, and you'll have your efficiency.
I measure my pre-boil gravity (and first runnings), but it's not necessary unless you are using the length of the boil to adjust for missing your target.
Conical 1 - Just cleaned out.
Conical 2 - Empty
Carboys - None
Secondaries - None
Lagering in Kegs - Bavarian Dunkel
Kegged: Belgian Dirty Blonde Trappist Ale, Forbidden Fruit IPA, Double Chocolate Stout, Bourbon County Stout, BLC
Bottled: Oaked Bourbon Porter
Planned: Looking for ideas