hope, my school-english ist good enough - or better my remember of it- to explane:
you must not unstall every time, you can use the MultiModSwitcher -take a look in the downloadsection- install it in your Sust2-directory, after the installation of the mms you install the mods you want to play. it works with every free mod. i`m not sure, if it is necessary to install the mods after the mms, but in that way I`m sure that it works. With the mms you can choose between the original and every mod you have install. Maybe you had to press "fix config" when you start the mms first time. Then the mms gets closed, start it again und then play, whatever you like.
Hope you understand my try, if not, ask again, here are some guys, who speeks better english than me

Exilant