There is no problem with the unit taking you to the field.
Request an Exception
Since it took 6 weeks to get this appointment an exception might be warranted. Usually if you take this up the chain of command the CDR/1SG will make an exception that will allow you to go to your appointment and get picked up for the field later in the afternoon. If the 1SG/CDR will not make an exception consider seeing the BN CDR/CSM on open door policy and/or contacting the IG.
Final Out or ETS Physical
As a senior leader I did not take Soldier’s to the field or allow them to participate in activities (PT, unit sports programs, field duty, etc) in which they might suffer some type of physical injury if they had already completed their final ETS physical. My rationale is that I did not want them extended beyond their ETS date for treatement. Now this was something I did. I do not know of any regulation that requires this action.