Re the extreme bounding box, the good news (for me) is that SAMM isn't at fault. The even better news is, SAMM can fix it (if you want to be bothered).
The HH-65C model contains over 33,000 vertices, the positions of about 6300 of which could be considered extreme. It is these latter vertices that are causing the bounding box to be so large. Their use is a mystery. Perhaps it was some test capability that wasn't deleted. Unfortunately, even if I disable all animations (using Animations: Custom), a few of these extreme vertices are still used. So, if you go out along the boundary of the bounding box in FlightSim and look hard enough, you'll find a few triangles drawns. Some will be untextured, others will use some part of the texture Misc_T. bmp.
It's not possible to tell from the .mdl file to what these vertices are related. But, even with Animations: All, only a few of them are used and only in a couple of places. If you really want to make the bounding box normal - what you can do is, in the aircraft .mdl listing, locate the DRAW_TRI commands which use these vertices (21601-27915) and use SAMM's "delete" function on those commands. (It doesn't seem likely that their rendering contibutes significantly to the displayed model.)
But, I'm going to change SAMM anyway so it considers only the vertices actually used in the rendered model when setting the bounding box dimensions. In the case of this helicopter, this wouldn't fix your bounding box issue, but it may prevent it occuring unnecesarily in other models.
Don