To do it the most simple way, just create a basic .vimrc (and/or a .gvimrc - I have all common settings in my .vimrc and source it from my .gvimrc) with options that you will always want. Then create two separate files with the commands/settings you would want for each mode and simply source them from vim: Open vim (it's in your "basic" mode) and just type :so docmode
or whatever you have called your file.
This could also be implemented with functions in your .vimrc I guess, but I haven't dived that deep into the workings of vim scripting. Also, make sure you check the tips and tricks section of the vim website