I follow a convention in variable naming:
s_xyz - string
b_xyz - bool
go_xyz - gameObject
...
It would be great if playmaker recognized those prefixes and automatically preset the variable type based on these.
To support various conventions you could add a simple mapping file (like java properties file) with bool=myPrefix, float=myPrefix, etc.
Or even better make a gui for that ...
Many thanks!
EDIT:
Keeping consistency when renaming such variable would be great. Even if it means only a reminder to change the prefix manually.