Good idea on the pond plants. I think that I'll stick to floating plants though as I don't really want soil in the system if it can be helped.Personally, I would increase that rate closer to 20% per day. Just to get to at least 100% turnover per week. Also, water plants will be beneficial for water quality purposes, as well as aesthetics. Plants that requires soil can be planted in pots.
In regards to mechanical filtration, instead of using wavewakers, why not utilize a water pump. Pump water up to a large tub above the pond, and drill large holes towards the bottom of this tub as drainage ports back into the pond. Fill the tub with inexpensive polyester pillow stuffing, to act as a mechanical filtration media. Water from pump dumps out on top of tub and on to polyester, water works it's way down to the bottom of the tub, and exits drilled holes back into pond. Setting the tub about a foot above the pond's water surface will create agitation to provide water movement throughout pond, and aid in oxygen exchange.
You may also have an issue with green water due to algae growth. Tinting the clear roof may help, or you may have to cover the roof with a tarp most of the time.
I am hoping that I won't mechanical filtration as I'll have a fair amount of water flow to agitate the water, allowing for the solids to be held in suspension and then drained away on the overflow. I might be wrong though, and there is an element of trial and error.
I will have extensive aeration too.
I've had a good quote for a preformed fibreglass pond 16ft x 8ft and 4ft deep so I won't be building one. This is a smaller version of what I'll be getting: