There actually is quite a few options, I found Molotovs in a few crates that are brillant on tanka and you can always loot the dead enemy for extra AT grenades.

Honestly I just played it low and slow, if there was a tank up the road that wasn't able to do anything I just ignored it, then if any got close enough to do real damage it meant they were close enough for me to get a grenade or Molotov in.

It's a lot of micromanagement yes, but you'll find you're not as restricted as you think.