Yup, you can be one. Here's a shot of the rear cockpit so far.
Click to enlarge as usual.
In case you're wondering about the orange panel on the centre console its technical name is the "Trainee Instrument Fault Simulator Panel", but a better description I think would be "Panel of Misery". ;)
The switches and levers on it let a rear seat instructor fail just about every single instrument in the front cockpit, in several combinations, including all electrical power, while everything in the rear pit continues to work normally. It's fantastic for partial panel or IFR training in Shared Cockpit. Most of the instruments in the L-39 are electrically driven and if you flip every failure switch at the same time then the only remaining reliable instruments in the front are, and I kid you not, the fuel quantity indicator and the slip ball. That's it. :)
Flip all those on someone at night or in cloud and you're going to be in for a lot of verbal abuse.
I should also mention that despite not having a huge 'step up' for the rear cockpit, visibility from the back seat of the L-39 is really good, and on a standard three degree approach you can easily maintain sight of the runway threshold and centreline until the very end of the flare.