Sub: That carpet covered MDF automotive enclosure will last a season or 2 in a boat at best. If you are looking for a marine-ready sub/enclosure option thats ready to go, look into the Kicker SKM-10 or build your own enclosure out of void-free birch thats rosin coated inside and out.
For your tower speaker option, what exactly are you looking for in terms of listening goals? $1700 for a pair of 6.5" and 5.25" speakers and lights may not be the best investment. A single pair of larger HLCD's would offer music for wake-board range and warmth at surf range, and would come in about the same with an amp included.