Just a WAG:
Patton’s 3rd Army was in Czechoslovakia in May 1945 and the XIX Tactical Airforce assigned to the 3rd Army. There were at least two Mustang Fighter Groups in the XIX, the 354th FG and the 363rd FG. There were also some F-6s in reconnaissance units.
Here is a link about “Air Power for Patton’s Army”:
https://media.defense.gov/2010/Sep/2...100924-003.pdf
On the link of “The Air Force Chronology” for May 1945 here:
http://paul.rutgers.edu/~mcgrew/wwii...ml/May.45.html
Search for Monday 7 May and Tuesday, 8 May:
It appears the 8th and 15th and 12th AFs get ruled out, but note comments for the 9th AF and in particular the XIX Tactical Air Command:
7 May:
TACTICAL OPERATIONS (Ninth Air Force):
The XIX Tactical Air Command flies
sweeps over E Germany and W Czechoslovakia and carries out demonstration
flights over prisoner of war (POW) camps
8 May:
Ninth Air Force: The IX and XIX Tactical Air Commands patrol the Leipzig,
Chemnitz, and Adorf, Germany and Linz, Austria areas, and fly sweeps and
demonstration missions.
Note: no mention of flights over Czechoslovakia on the 8th as they had done the previous day however some the areas they did fly over on the 8th of May are very close to the border.