Ali: Applying little common sense will give you an answer far better than we on this forum can:
1) Go measure the height of you on-shore shower "stub-out" (where the pipe comes out of the wall to your shower
head. You'll find that that is 6'6" (= 2 m.) above the "decksole" (floor) That inplies a height under
deck of 7 Ft. (= 2.10 m. [min]) So right there is one of your search parameters when you look for a
boat that will satisfy you. For the 10K quid you state as you
budget, that can't be done!
2) For your
budget you aren't gonna get anything worthwhile that's more than 30 ft. on deck, say, 9.50 m. Your total flat "floor area" will be less that 20 SqFt (2 m^2) and that will typically be disposed as 10ft. x 2 ft. ( 300cm x 60 cm). You don't want to destroy any of that for something so trivial as a stand-up shower.
3) Your heads (W.C) will typically have a floor area of 75 cm x 75 cm, and not all of it flat, but all of it
outboard of the the fore-n'-aft
passage twixt cabins, and none of it at the same level as your
cabin decksole. Thus, to install a stand-up shower in the most efficacious place is an impossibility
4) Judging by your stating your budget in quid, you're in the UK. Thus, showering on deck, which is what most of us do, is no fun in the
winter. The solution is to accept that one of the prices you have to pay for
living aboard a
small boat is that for much of the year you are restricted to having a "Liverpool wash" aboard, and showering only in marina facilities or when visiting shore-side friends. In the UK, for much of the year, I'd be rather reluctant to have an "over-the-side-dunk", tho admittedly the
Gulf Stream tends to ameliorate the water temperatures. Here in the Salish Sea, despite our having a more benign climate overall, the water temperature thanx to the Japanese
Current is low enuff year round to make over-the-side-dunking unpalatable. In any event, if do have your ablutions over the side, you'll need to rinse with fresh water. Which you won't have enuff of.
"If you expect the impossible you WILL be disappointed. If you attempt the impossible you WILL fail!"
TrentePieds