Assuming you play e3 against the semi slav and ...a6 slav, you can try the 3. Nc3 Nf6 4. e3 move order. 3. Nc3 dxc4 and 3...e5 are nothing to be afraid of. Otherwise you have not much choice but to go for 6. Nh4 and 6. Ne5 lines. The former will cut down your workload by half, but my suspicion is that going into the 6. Ne5 main lines is stronger.

Of course there are other variations but to me these lines look most healthily aggresive.