Here are student examples of ‘just’ pre-modifying a prepositional phrase.
I was a shy girl and sometimes I was just like a boy.
TLC, speaking test, female China B1
Some successful people are well-known just in their country.
PELIC, female Arabic level 4 writing class.
In the English Grammar Profile, A2 point 3 in the category of PREPOSITIONS is defined:
‘JUST’ + to modify prepositions.
An iWeb search for:
just_R _II
1 JUST LIKE 495187
2 JUST IN 139921
3 JUST BEFORE 128761
4 JUST BY 84874
And just by bad luck, he did it to you.
Here are the rest of the prepositions after ‘just’ in order of frequency and tagged by CEFR level: