Two layouts: solution A is the softest intervention while solution B is in my opinion the most efficient scheme lying in your budget. In solution A no change to the hydraulic system is expected but the shower pipes; in B solution you will need to move the door - not an expensive work - and to make some minor changes to the plumbing: in return you will get a comfortable shower (90x100) and nice architectural solutions eg the nice bow window-like seat. Materials were chosen to achieve an elegant, intimate and warm ambience.