Precision Power doesn't publish Xmax for the Sedona subwoofers, which is bizarre. JBL Power subwoofers are all 5 ohms nominal, so your 200W @ 4 ohms would make a little less power. Xmax is 0.3", which is typical for a low power subwoofer.
A ported enclosure tuned for a large bump in the frequency response is the only sensible option if you have a desire to maximize loudness. If it must be a small sealed enclosure you need more excursion and a lot more power.