Historically the 20" we have ran in the North Sea has been of a 1/4 or 3/8 turn for make up. So no issues were observed with the stabbing and make up of these connections.
The concerns raised could be mitigated by using a mechanical stab-master or the use of the rigs drill pipe racking arm to keep the casing central.
As always we would recommend use of stab-in guides these would usually be supplied by the TRS provider.
Use of a CRT (Overdrive or other variant) would be highly beneficial also but this all depends on the length of string and requirement to wash casing down etc.
Hope the above helps please feel free to reach out if any clarifications are required.