Peter, this is why I stated to drive the screws from behind from under the deck through the 2x2 or 2x4 (essentially the block) , nothing will go into the fascia board from the front because of the pool.
Building the block and fascia before installing won't work since it will be too thick to fit through the 1.5" opening - you could however, slide it in place from underneath, hold it up from underneath while someone else drives screws through the last flat deckboard into the block to hold it all.
Yes, to put a winter cover on the pool, the whole rig would have to be removed, however, if there are little or no trees around, I would not bother with a winter cover since it's more work and aggravation and can damage your pool if done wrong in comparison to throwing the cleaner in come spring time.