I'd definitely try to put in one of those sumps shown on Vic's link. It would be a worth-while addition for both shower and AC output.
Newer Sea Rays use the Rule version. There are a couple things I don't like about it, though. The cover is screwed down, and on my boat it is quite difficult to undo all the screws to clean out the screen. My cordless drill won't fit in the space. Also, to prevent the pump from cycling when water drains from the hose into the box, Rule uses a rubber check value. The problem is that (on mine, anyway) the pump would not get the water through the value, so the pump ran continually. Seems like a poor design. I had to remove the stock valve and splice in another type.
On odor, I've found that even with a sump you can get bad odors. My head had a nasty sour odor that was hard to locate. I tracked it down to the shower sump, coming back up to hose. Now I flush some enviro-friendly Star Bright bilge cleaner down the drain from time-to-time and after every use of the shower; odors are greatly reduced.