Monument Valley Navajo spirit tour

Heading to Monument Valley early August with my parents in their 70’s. Navajo Spirit Tour has backcountry tour and sounds appealing but would the tour be senior friendly even with my mom with back problem? Her back problem is not too serious but some Jeep tours I heard are very rough. Also what time of the day we should do the tour? We are not staying at the View Hotel unfortunately (was fully booked) so maybe the sunset would be the best? Many thanks!