Midas- the shower drain plumbing is above the plumbing bay which is tough to get at on the underside; if its req'd you will need to saw out the plumbing bay panel in a way you don't hack up the water piping behind it.
You can remove the shower to get under it; there is a trim strip held in by brads around the shower enclosure lip and screws behind the strip. Remove the shower door glass panels, disconnect the drain from above, disconnect the shower valve escutcheon, unscrew the enclosure and I believe you can dance the shower enclosure out. A waltz tune is best, I'm told.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project