No need for a full cockpit. You can also make some switch panels. All you need is an interface-card which is able to do keyboard emulation and some cheap switches.

I use Pokeys cards in my pit, but there is also the option to use Arduino's. There is a software for the Mega for example, you could make an easy to built an really cheap switch panel (or box). I used this for my retro rig. It runs with every program not only with the FSX. Could be a way for just experimenting a bit with it. The Arduino clones are really cheap at Ebay, so if you don't like it, there is not much lost.

But be careful!! The simpit-virus is extremly infectious and it seems that most wifes or girlfriends are totally immune to it

Here is the page with the software for the Arduino Mega:

http://www.jimspage.co.nz/arduino_keys_beta.htm

There are also tons of tips here in "Flight Sim Controllers" and "Flight Sim Pit Builders" in the forum. A small switch-box or panel does not need much room and can easily be put away at any time