Late to the party.
Hello there, I'm north of Bastrop in Morehouse Parish. There are indeed no LSM sites around. Monroe Site & West Monroe Site are on two different frequency sets. From my experience with the LWIN in this area, Bastrop site tends to have better coverage in Sterlington. However most city services tend to only transmit on their "home" site. Parish services tend to transmit to surrounding parish sites.
Example:
Morehouse Parish SO - I've heard on Bastrop, Monroe, West Monroe, Marion, Oak Grove, Delhi
Bastrop PD - I've heard only on Bastrop
Ouachita Parish SO - I've heard on Bastrop, Monroe, West Monroe, Calhoun, Farmerville, Oak Grove, Delhi
West Monroe PD, Monroe FD, WM FD, ULM PD - I've heard only on Monroe, West Monroe, Calhoun
Every once in awhile, Monroe PD will come in at random on the Bastrop site. But not always. It is ALWAYS on the sites in Ouachita Parish. I assume all this is priority based as when I do hear a neighboring parish TGID, it's always law enforcement. I've shuffled around scanners and so far my current task is finding new TGIDs and DMR systems in the area so I'm a little out of date. If you can pick up Monroe site, you should be able to site hold, keep it from switching to Bastrop and thus hear the local Monroe area stuff / Morehouse & Union Parish SO's. If you want to listen to Bastrop local ID's then swap over and you'll still be able to pickup OPSO/UPSO in the process. Sterlington PD is on both sites. LSP & LDWF can be monitored on either site (or any in our region).
As for the antenna; the newer the scanner I get, the crappier the stock antenna is. My stock antennas for HP2 and 436 did okay but not the best. My stock antenna for the SDS100 was horrible. Any Diamond or Remtronix aftermarket 800mhz antenna will do wonders for systems around here. I also love my SpectrumForce in the window. I've never used a 996XT so I cannot speak for it's stock antenna. But I'm willing to bet that any aftermarket antenna would be an improvement.