are you aiming for a specific, very important target or are you merely out to attrit enemy land forces?
if the latter, i would advise using a AI/BAI mission instead, where you will get success for damaging enemy land forces. if you are looking for a very specific target the best idea is to fix where they are, examine the terrain, examine what they are doing (garrison, movement, engagements, etc) then recce as you move in from ~20nm slant with FCR/TGP combo. with careful reconnaissance picking battalion TYPES out of a huge horde is probably possible, but ultimately you should never expect 100% success rate if you are looking for a specific battalion when it’s thrown together in a sea of ultimately pretty similar battalions.