Seeing as gravity is providing us with a convenient source of 1G of the top of the loop, it's pretty clear that of the loop is large and the speed is low and you need less than 1G over the top of the loop then your wings will be producing lift towards the wheels to cancel out some of that 1G.

So yes, it's quite possible for your wings to be producing lift towards the canopy all the time in a small fast loop, but also transition from producing lift towards the canopy to producing lift towards the wheels if you loop is big and slow enough. Depending on how big and slow you're flying depends if you need to hold in a bit of down elevator or not to. I've never had to with my pattern ships, but a nose heavy, underpowered sport thing huffing and puffing it's way over a loop just might need some.