You’re missing the point. If the Senate actually goes into recess he can then make all his appointments during that time. There will be no constitutional issue.
The problem is that the Senate has not officially recessed during holidays. Someone stays behind to keep bullship activity going.
The simple solution for the new administration is for the Senate to adjourn in observance of MLK day. It is a Federal holiday. It is also inauguration day. That would mean Trump could appoint anyone he wanted on his first half day in office. The Senate would not have to approve any of them.