Well, I don't use MEPv6 and can't answer the questions...but...
You can always change the light factor in the Mod file back to the value used in GWX and see if that gets you back to suitable distances for sighting your boat at night. Just keep track of what changes you make so that you can undo them again if they cause some other unwanted problems...and be sure to do the tweaking when the Mod is disabled.
I've done that many times to tweak many Mods that I use. Since I do a lot of experimenting with various changes to .cgf files in Mods, as well as .sim and .zon values (using S3D), I also keep an "untweaked" original copy of the Mod handy, in case I really screw something up.
Give it a try...good luck.
