I initially intended to have the WH there, but access is still an issue.
Note which side of the framing is dimensioned. The clear space between studs is 5'-1." I may actually increase this for a roll-in shower unit once I check some commercial options.
I thought about a solid ridge beam and rafters like the original 1947 house had, but trusses are the cheap and fast solution, and adding a stairwell for an attic and basement would add a lot of extra complications.
And yes, even I remember when land was as low as $1-3k/acre in my rural area. No more. Bare land costs more than my parents paid for 10 acres and a house almost 30 years ago.
The access to the WH is a door to the outside.
Insulated door in colder climates.
You want it there because water heaters burst all the time, and you want the water to flow outside.
The one piece tub/shower unit is just a hair under 5'-0".
So, the opening is that, plus 1/2" for the drywall on each side.
For most of the one piece units, you shim the unit to the wall studs where it needs support.
That million dollar house, is $100k house + $900k property. It really wouldn't make a difference if you could make the house for half price $50k. But, really $100k is a cheaply/poorly built house already.