In your 3rd picture, click on the blue dimension that says 3.07 and then when the edit dialog box appears, click the lock symbol. This will lock that thickness value down for you so it won't change when you adjust your other dimension from 48 to 53. You can also do the same thing on the bottom of the part.
a box selection of the upper surfaces followed by a change of that dimension doesn't do exactly what You request?
This IMHO should be no problem.
That mean a simply "stretch" as in former times with 2D CAD