Bat men use the animal person variation, which makes their size the average between the size of bats (100) and 70,000. If you want to change them to size 70,000, you should be abble to do so by changing their raws as follows (the lines starting with > are the added ones):
[CREATURE:BAT_MAN]
[COPY_TAGS_FROM:BAT]
[APPLY_CREATURE_VARIATION:ANIMAL_PERSON]
[APPLY_CURRENT_CREATURE_VARIATION]
> [GO_TO_TAG:BODY_SIZE]
> [CV_REMOVE_TAG:GRAVITATE_BODY_SIZE]
> [CV_REMOVE_TAG:BODY_SIZE]
> [APPLY_CURRENT_CREATURE_VARIATION]
> [BODY_SIZE:0:0:70000]
[GO_TO_TAG:BODY]
[CV_REMOVE_TAG:BODY]
[APPLY_CURRENT_CREATURE_VARIATION]
[BODY:HUMANOID_FLIER:2EYES:2EARS:NOSE:2LUNGS:HEART:GUTS:ORGANS:HUMANOID_JOINTS:THROAT:NECK:SPINE:BRAIN:SKULL:4FINGERS:4TOES:MOUTH:TONGUE:EYELIDS:CHEEKS:GENERIC_TEETH_WITH_LARGE_EYE_TEETH:RIBCAGE]
[GO_TO_END]
[SELECT_CASTE:MALE]
[CASTE_NAME:bat man:bat men:bat man]
[SELECT_CASTE:FEMALE]
[CASTE_NAME:bat woman:bat women:bat woman]
[SELECT_CASTE:ALL]
[APPLY_CREATURE_VARIATION:PUNCH_ATTACK]
[APPLY_CREATURE_VARIATION:KICK_ATTACK]
[APPLY_CREATURE_VARIATION:NAIL_SCRATCH_ATTACK]
[APPLY_CREATURE_VARIATION:TOOTH_BITE_ATTACK]
[APPLY_CURRENT_CREATURE_VARIATION]
[GO_TO_START]
[NAME:bat man:bat men:bat man]
[DESCRIPTION:A humanoid with the head of a bat and wings stretching from wrist to ankle.]
[POPULATION_NUMBER:30:50]
[CLUSTER_NUMBER:5:10]
[MAXAGE:20:30]
[CREATURE_TILE:'b']
[COLOR:0:0:1]