Since WA5MD Tim's stated question "Is this not the proper way to log these vacation contacts" is about uploading to LoTW, he might also consider asking in the LoTW Groups.io topic, or at the ARRL web site, since they operate the LoTW program.
 
For over 45 years.Part 97 of the FCC Rules has nether required nor mentioned the /P ID format.  The generally accepted method of identifying when operating within the USA but away from your home QTH is your assigned call with no added prefix or suffix.  The message formats utilized in WSJTx FT8 do not allow for insertion of random free text characters (such as /P), but when using WSJTx digital modes you do send your current grid square.  Logging enhancement programs such as JT Alert or GridTracker DO check the grid square when qualifying a true duplicate contact. 
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Karl  WA8NVW  OH
WA8NVW@...
in WSJTX@groups.io