How big is the wicking hole? The size of the holes in the wicking cup should be less relevant. If anything, I think the cup might be too big of a 5 gal container. You did drill holes in the aeration bench? Air exchange is important, but getting the proper wicking action is too.
Top watering and feeding is always an alternative until you get the mix right.
Assuming you work out all the kinks, you might have a humidity issue indoors when it comes to pollination and fruit set. But you can deal with that when the time comes...
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