The S-Ride Gravel Rear Derailleur supposedly clears up to a 46T cog in a 2x configuration, has 49T of chain-wrap capacity, and should work with any Shimano 11-speed road/gravel mechanical shifters, as well as Tiagra 4700 and GRX 400.
If you do try this, be aware that there is no cable tension adjustment at the derailleur. You’ll need an inline adjuster to set your indexing.
Before this became available, I made a Frankenderailleur out of a Tiagra 4700 GS upper and a Deore LX RD-T670 SGS cage. It clears a 40T cog without a RoadLink or similar extender, and has chain wrap to spare with an 11-40 cassette and 50/34 chainrings. I think* *it would clear a 42 without a link, but I’m not sure. If you have 5800-series 105 and can still find the RD-T670, it would work the same.
The 105 7000 rear derailleur is different, and that cage won’t work. I’m sure if I scoured Shimano’s exploded technical drawings, I could probably find an MTB SGS cage that would mate with a 7000 upper half.