If I was told that I was going to spend the next 6 months on a desert island and could take only a basic modeling tool kit, I would probably take the following:
Exacto knife w/ pack of 100 blades, flush cutters (sprue cutters), a tube of 1 body putty, 1 set cheap kneedle files, 1small Zona saw, 1 straight nosed tweezer, 1 angled (45 degree) tweezer, couple of sheets each of 360,400,600 & 800 wet/dry sandpaper, 1/2 doz cheap paint brushes, 1/2 doz really good paint brushes, glue (mine would be liquid, CA and epoxy), pair of good small scissors, a 6" steel ruler, paints and thinners of your choice and of course a fishing tackle box of a sufficient size to store all the above.
The above is pretty much what I used for the first 10 or so year is was in this hobby. I think that most of this stuff can be found w/in a 30 minute drive from my house.
Hope this helps a little