"- Does anybody have a thought on the Wetsounds Pro80 vs. the Exile XM7?"

Well, you can't compare the two different sizes, even if it's from the same brand. The Exile XM7 is a 6.5" HLCD with a fraction of the pod displacement while the Wetsounds Pro80 is an 8" HLCD (the size of an XM9) with considerably more pod displacement.
The Exile XM7 was head to head with the now discontinued Wetsounds Pro60 with the same speaker size and similar pod displacement.

Nothing will touch the Wetsounds Pro80 for the dollar (brand new for $699) in ampitude or projection power. The Wetsounds Icon8, Rev8 and Rev10 will provide stronger sound quality than the Pro80 for near field listening as they have a bit tamer response. But frankly, you will not see a SQ difference at the end of a rope in the face of all the noise competition. At wake range, your only priority is cutting through with enough amplitude to hear a degree of articulation.

Adding a subwoofer to the in-boat zone has very little impact on the tower. The sub's bass will not project to wake range. The two speakers (sub and tower) play different bandwidths with little overlap.

Amp mounting techniques will differ based on the scope of amplifiers and distribution products mounted to the panel. With a multi-component amp panel, most build a new panel and mount the panel to the existing provisions.