i would think any move to a road bike will be less relaxed and upright. for this reason,
it's more common to move to an mtb for comfort or lower back pain. you won't know
until you ride some demo models at your lbs. or you might try a new, longer fork...
add spacers instead of cutting to raise the hbar height.

have you considered a recumbent? aerodynamic, no stress on sitzbones or lower
back, and with underseat steering you can't lean on the bars in any way.