Well if they stop spawning vehicles entirely there is nothing you can do that’s the worst that can happen. But as long as there is APCs or Tanks you are good since you can pen majority of Japanese and German tanks up to BR III. But if they turn to infantry completely there is nothing you can do but thats why you can combine it with ground attacker or another CAS plane. If you have only one slot no point running it but if you have the French yak 3 you can combine it with IL-2M much better combination then running other planes. The only reason to run only BR II fighters is if you really have only 1 spot for aircraft but if you have two vehicle spots and you wanna be a pilot I dont see why I will pick Yak-1 or P-40 literally my main enemy is Ki-100 that will absolutely destroy me in a fight. If you have multiple slots better run Yak-3 and IL then some mediocre plane that dont even have rockets. I mean if you play BR I or BR II its ok but at BR III this aircrafts lose value and god forbids you are against BR IV match you are just flying a brick.
The Yak is low altitude fighter you dont need to circle in the sky you can hide or make boom and zooms . The only problem is if they just ignore you and dont spawn vehicles then there is not much you can do. But most of the games the enemies are spamming vehicles all the time thats why the Yak -3 is very anti meta aircraft. So normally you spawn IL-2 after few rocket runs I can guarantee someone will come to take you down but since im running 3 aircrafts I can rotate non stop fighters so for me is not a problem 
In General I dont understand how can you play P-40 or Yak-1 your main enemies are Ki-100,Zero,Ki-61 and BFs and FWs all this aircrafts can absolutely destroy you and against Zero and Ki-100 or Ki61 really I don’t see what you can do not only they will bomb your teammates but they will farm you in the sky. You can only hope you surprise them since if they see you its game over for you. In a frontal engagement they will kill you in a dog fight they will kill you you climb is also terrible so you cant boom and zoom them literally they have all the cards. Your only option is really to surprise him.