I have fitted a 1TB WD blue ssd to my late 2015 imac 27”, it had no hard drive before, just the PCIe SSD. All I needed to source was the Sata/power cable. I did NOT fit any thermal sensor and it works perfectly, no fan spin or any other problems. I also replaced the PCIe SSD with a Samsung NVMe 1TB unit with an adapter, this also works perfectly. I conclude that at least on late 2015 model. NO thermal sensor is required. The system reads the drive temperatures fine so they must now use the Smart data. Its been working for 3 months now like this, don’t waste your hard earned money on un-neccesary stuff.
To the travel question, I am transporting mine on a flight. You need to remove the screen then the psu and logic board. There is a row of 9 xT8 screws where the stand attaches, remove these and the stand comes off. the reverse process is needed at the other end or alternatively fit a vesa mount. This is a workaround as the screen needs to come off every time, not ideal but workable for me as I’m only doing one trip and I want to change the PCIe SSD anyway.
The magsafe connector has a small chip inside which is programmed with the magsafe psu serial number and other data including the power rating. If you put a cable from a 60W supply on to an 85w supply it will report it as a 60W supply with the serial number from the old unit. eBay/Ali express replacement cables carry the same problem and have all 0000 serial numbers. same as aftermarket chargers.