Make a division with 900 OAAB and the rest MRMB. The recommended amount will probably do for WL2. At least 50K I'd think. With this you will attack defenses at either a heli unit or an undefended target somewhere farther than 35 mi from any ground units. At some point no helis will respond meaning they are gone.
Next you got to figure out if there are any ground units within 35 mi. This last time, I just attacked with 1 weapon each and checked the report to see if any ground units responded. If they do you need to just attack an undefended target or another heli unit farther away from the ground unit. It may also be that there are no ground units at WL2, I can't remember.
If your just working the WLs to get GC I'd just avoid the C3s where those offensive bases are close together. That will ensure it's easier. Because you cannot destroy the air units without attacking them directly. They typically don't get resupplied with equipment, but as long as they exist they can return to full strength. So getting rid of them is just easier if you don't have the ground units to deal with.
At WL2 there are usually enough undefended targets that you can win the war without touching the interceptors or ground defenses. Just put toghether some type of unit that has HA and/or HT with around 50k of shells. Then just use your radar planes to locate targets that aren't defended and attack target with the HT/HA. In the absence of Heli coverage, there is nothing to stop this. Just don't attack garrisoned targets or any target within 35 mi of a ground unit.
It should basically be really easy, just kill the one or two heli units, and start leveling. You may be able to get through level 4 or 5 before you have to learn anything else.
Just make sure you get the maximum painting damage quickly.