I can totally see something like this being banged out on planets that aren't exactly backwater, but also don't have any major industries.
Small support vehicles don't use full-blown armored turrets. They use pintle mounts instead. The upside is that it doesn't count as a location, so you don't have to armor it. The downside is that it only has a 180 degree firing arc. But, now you can armor the rear or have it survive two SRMs to the front.
Also, you don't need to include any ammo in the turret. The first 75 shots (well, 15 bursts) are free, and the pintle mount doesn't actually hold ammo. That's all in the body.
What tech level are you using for the body? Your armor and engine seem to be D, but the chassis should then be 153 kg and I don't get 320 kg for the cargo.
My hat is off to the name of your T&T system, by the way. Truth in advertising at its finest.