What faff will you save?

Fixed PA will be either pa at 100 - which will usually be blurred below 20, or fixed at airgun ranges which mean blurred further out.

You are far better in your case having a front PA scope and leaving it PA at 25 yards for the squirrels, if you don't touch it the PA is fixed

You have always the option then of bringing it in for rats and out for stalking / observation.

We marketed a scope exactly for this purpose, the Cobra. This is being discontinued due to the popular demand for side P/A