You just answered your own question.
Not even I, as reckless as I may be, would not put a deathstar like that in a small point game like this. Too many eggs in one basket with not enough support.
Split that into more slugga-trukks perhaps, or put a whole lot of shootaboys into the battlewagon instead w/ big shootas all over the place. You will need them for being awesome and for shooting aircraft, because Imperial Guard and every other army can take a nasty flier at 1000 to harass the heck out of your army.
Most armies can take a lot of simple counters with the amount of points you put into those nobz and have the rest of their army overkill the boys. You really need to save the nobz for bigger games and take more boys.
I speak from experience
Cheers,
DaK