Unless you are changing them on a regular basis, the cells  with the hours in
them don't need to be anywhere near the "H" cells or the formulas - they can
just as easily be on a different sheet.

In most instances, these hour values would be common either from day to day
or from week to week, and probably even from person to person. This would
mean that you don't need an hours value for every day anyway - you could
have all the formulas referring to a few common values.

However, I don't know your specific circumstances. If you want to keep this
information close to the other information, then that's fine, and you just
need to protect the cells at the same time as you hide  the rows.