Blue Star Cheezing update:
the progesssion getting them, using my T7 Chally method has been as follows:
B = Blue Star
x = anything else
B-(B)*1-B-B-B-x*2-B-x*3-x*4
*1. I did a silly thing on Harbinger, and got killed - I haven't memorised the positions of all the spawns, and moved too far into the town before the last wave and got killed - so I got the Blue star but it didn't count. Entirely my fault.
*2. 1x Tier 8, Griffin 50mm did so much damage I couldn't keep up. I came 2nd
*3. 2x Tier 8 griffins, no chance. I came 3rd
*4. 1x T8 Marder2 + 1x T8 Ramka99, the same. I came 3rd
I think I see a pattern here: against my own tier, playing only Rolling Thunder, Harbinger, Starry Night, Life Jacket and Wildfire, I honestly think I could get the blue star 9/10 times, now I know where to go.
HOWEVER:
The MM keeps sticking me with super-machine-gun, shredder vehicles, one tier ABOVE me. And even if I do 12, 13, 16k damage, if there's a T8 vehicle doing 26k damage, even if I spot ALL his damage, I don't think it's mathematically possible to beat them, using my method, because of the extra points they get from being one tier up.
so on to plan B ...