I reckon I've read something about the Baja model somewhere, but can't remember much of it. I believe it was intended and/or used in a Paris-Daker attempt without all that much success.
This site is not 100% reliable, but here are entries for the TT and the Baja. The text is the same for both, and appears to relate to the TT rather than the Baja. There are, however, two photos on the Baja page that are visibly different to the standard TT.
https://www.motorcyclespecs.co.za/model/moto guzzi/moto_guzzi_v65tt 84.htm
https://www.motorcyclespecs.co.za/model/moto guzzi/moto_guzzi_v65tt_baja 84.htm
Following the TT, there was also the NTX 650 and NTX 750. I gather that they were both better than the TT in a number of respects, but don't know the details.