Hi Bryguy,
Rather than the Topeak Explorer, I would get the Topeak Super Tourist. Pic and link below.
It is a little bit more robust and additionally it has a lower "rung" where you can choose to put panniers lower if you wish. This model is the "uni" version meaning it is designed to be more universal and fits most bikes.
https://www.topeak.com/global/en/pro...urist-dx-(disc)
From there, you can choose to get a Topeak bag or Ortlieb (or both.)