Being as the temperature where you live is fairly mild I would opt for a bottom drain, possibly a small vortex, a laser-cut screen sieve and then some sort of TT. You can easily put the TT out of the way, off to the side by letting it drain into a catchment above the pond level and then connecting this to the pond with a somewhat larger diameter return With a little ingenuity you could even install one above the other if the size of the foot print is critical. This would reduce it to about 3'X4'
You should have seen the girl working in the supermarket lose it when I went in to buy denture creme for my fangs on the night of our Halloween party She ran screaming "Get away you scare me". Of course I chased her!