Assuming we're talking about a fresh water leak and not a drain water leak??
It appears your RV is a 5'ver. Is that correct? I googled your listed model.
If this is your floor plan, look behind the TV in the cabinets for an access. If no access, you could easily cut something out, directly behind the shower valve.
It might be as simple as a loose nut on the shower valve body.
Removing the shower is absolutely the LAST resort, IMO.