One of the reasons I have been less than enthusiastic about using my RF 100-500mm L lens with the RF 1.4x extender has been the lack of a fully satisfactory way to carry the kit.
But the LowePro Protactic TLZ 75 AW ll has come to the rescue.
With the lower section of the bag unzipped this bag accepts the RF100-500mm with the RF1.4x extender and the R5 body mounted ready for action. Even better the substantial top compartment is able to carry lens caps (required if the extender is removed), batteries, puffer and cleaning cloth with no problems. The reverse mounted lens hood fits snugly into the extended bottom section of the bag.
The bag has a rain cover if required, several carry handles and an extra slim pocket on the outside. There are two straps with various fittings which allow the bag to be carried in several different ways depending on individual preference.
If one is going out without the extender the extendable bottom section can be zipped up to reduce the overall depth.
The tripod foot can remain on the lens, rotated so it fits into one of the corners of the bag.
I believe the bag came onto the market before the RF100-500mm lens so the fact that they match up so well would appear to be a happy co-incidence.