I found it useful to install a shut-off valve if I only wanted to use the main tank for short flights. Remember that the fuel guage reading in ground attitude is vastly different than flight attitude; and in a prolonged climb the tank will 'appear' to empty rapidly - then appear to fill up again in level flight.

Also, I recommend pre-mixing the 2-stroke oil/petrol before filling. With just one tank I used to get away with putting the oil in the tank, filling to a 50:1 ratio and shaking the tail to mix - but this is not advisable with a rear tank as the mixture ratio will most likely be 'lean' in the rear and 'rich' in the front - causing plug fouling when throttled back.