That wold work, it's how I originally did it for my first attempts at games.
There's three real options when extracting the default RTP, the first is export everything you get by default into the C:\Documents and Settings\Mataris\Documents\RMXP\Game_of_the_Year\
(or wherever your game is saved), which will mean your game carries redundant files, increasing the file size (bad for those who are downloading it), but good in that since every resource is available, you can be sure you didn't forget anything (keep in mind, forgetting even one character graphic is enough to make your game crash! Making this a tempting option).
The second option is to just export all the resources you use, which will make your game smaller, but will take a lot longer to sort.
The third option is Rydin's approach, as you mentioned under the games under construction page here
, which tells you to copy all the default RTP files over to you game's folder, and since you can look at the files in explorer, you can see thumbnails for each graphic, making it much quicker to sort and remove the resources you don't use.
If you're not convinced, back your game up, try out the option you've picked, if it errors out, just select Game >> Select RTP and change it back to Standard, and look for the resource it mentioned was missing