Keep in mind too, that what I described is just one method of doing such a recce.
You might also approach it by first studying maps, aerial and ground photos, previous mission reports and so on and use them to identify potential harbour and OP sites.
Other sources of information could also be checked, such as travellers, merchants, friendly forces and so on to find out what they know about the target area. That could also involve the potential risk of tipping off the people who are in the target area!
But again, everything comes down to how much time you have before you need the information. In some cases, you might only be able to send a small team in for a few hours to check out the place and just hope they get enough intel.
When it comes to your scenario about the Texas Legion, you could send in a recce team to locate harbours and OPs but not with just further surveillance in mind. They would also be looking for places to site their own sniping hides.
The recce team leaves or could even stay in place to be the command & control (C2) for the operation. (I say sniping because as we know in T2k, there's no guarantee that you'll have proper snipers and proper sniping rifles. All you might have are hunting rifles or scoped battle rifles and some people who can shoot well enough!)
Once the team has the information they need, the sniping teams move in along with the C2 team (if it wasn't the recce team). The C2 team keeps the location under observation and whenever they have a good target, they radio one of the sniping teams to engage it.
The sniping team should relocate as soon as possible after firing the shot and move to another hide (or even out of the area if necessary). Another sniping team could have the opportunity to take out some of the enemy forces as they investigate. This has the potential to weaken the enemy ability to follow up your teams as they will have to split their forces to investigate each attack.
This scenario is a typical harassment fight, killing small numbers of the enemy and then getting away so they don't find out who's doing the shooting but it will obviously take a lot of time if the enemy forces are large
