Hi dwhite468

In your post you say you CAN do it using a dataset, so why don't you apply it into a calculated tag. IF I missunderstood your post then you will find some options below.

Create a calculated tag in PI:
if Hour('*') in 14 .. 19 = 1 then TagAvg('yourtagname','t+14','t+19') else NoOutput()

Create a Totalizer tag
Offset=+14h
Period=+6h
Function=Average

Give these two a options a try and let us know