I would say it will be tough with a level 4 attack, but the way I would try is to first deploy a shock trooper at ~4:30 on the edge. I don't know level 8 Tat that well, but I assume there is a trap near the hq. Next, deploy storms from 6 o'clock to about 3:30 on the edge as fast as possible (all 45, or however many you have). Once those are down, drop the VATST as close as possible to the hq, and hope it makes it to the hq and that the storms shield it. Put 4 twyleks in the SC, and deploy that alongside the ATST. I guess you could also go with an astromedic, two heavies, and storms. No matter what, it is very unlikely that a four can get it done imo.