Add a show/hide reading menu header and footer option in the Reading settings menu (on or off). For Kobo bought books and sideloaded books on Kobo Touch, Glo and Mini.
And when "hide reading menu" is activated use the full screen resolution of the device for reading. Not simply by hiding headers and footers while leaving these areas unused (empty) but actually reallocate them to the reading erea.
Default Reading area: full screen (resolution) -/- header -/- footer (in pixels)
And when hide header and footer is activated, the reading area shoud be:
Reading area: default book area (when header/footer are displayed) + header + footer.
This doesn't have to impact the tap navigation of the devices, as tapping on the middle of the page still opens the reading menu (headers and footers pop up).
And optionally, add new tapping areas that tapping only the bottom middle or upper middle of the page opens up only the reading menu footer or header.