All they can try do is counter mortar, which your field guns sit next to your medics getting healed and reinforced.
Just get a Jagdpanzer to deal with any tank aggression and back up with either fuasts or shreks.
Just dont panic because you are pushed back into your base initially.
If you're pushed back in your base and your way to get out is sniping maxims with mortars it´s going to take way too long against a decent player. And you've dug yourself too big of a economic hole if you give up the map for too long.