The new Pi5 offers PCIe and this is a good opportunity to create a fall back system and to check if measuring HDD temps without waken up the HDD is possible and with that to skip the external temperature sensors I used in the Pi4b setup The Heat issue solved by separating SATA HAT and Pi, now running close to four years.
The first idea was to adopt the design, but that would imply a PCIe extended FFC cable in the front which would not look very appealing. So I remember that in the beginning of the Pi4b setup I already tested an option with a „40 Pin GPIO Stacking Header für Raspberry Pi, farbig kodiert, 13,3mm“ with a slot cut into the aluminium case.
This basically worked out, but the USB3 cables I used at that time where very strong and not good bending for a small loop in back of the Pi, with them there was no option for a very short radius. Bridging the only few centimeters between Pi4b and the lifted HAT with bigger loops in the back did not look very appealing.
Today I know that I should have used the USB3 cables that come with the USB enclosures for external hard drives, as they are very thin and flexible and allow for much smaller loops.
But now on Pi5 and with Penta Hat’s short PCie/IPEX cable the stacking solution seemed to be a good approach.
Overall the wiring and the software adoptions I did are quite analogue to the ones described in the Pi4b post.
The new part is the approach with no more external sensors for the HDD temps which is working pretty well. To recap, the issues on ongoing, once a minute measuring HDDs temps with smartctl are
unwanted waking up a sleeping HDD
hindering a running but no load HDD to fall asleep
For „older“ HDDs it seems unavoidable, but on my two „newer“ 2 TB HDDs WD20SPZX there is a way. Unfortunatly hdparm and hd-idle both struggle and prevent HDD to fall asleep. So I wrote a kind of daemon python script monitoring diskstats and it sends no load HDDs to sleep with hdparm –y.
Hope you enjoyed reading and find it inspiring – have fun 
Michael
P.S. As a second 2TB SSD is on my Christmas whishlist the final switch to production will be in January 