The main question I have is, Is there 1 master table that drives the changes? Put another way, do you need triggers only on 1 of the tables. Or would a change in any of the tables necessitate pushing the change over to your target system.
Assuming the answer is you need changes from both tables to send a change over...
I've never done this before, but you could turn on SLT for both tables.
Create a view in ECC that joins the 2 tables together.
But then in in LTRS change the target table name to table1_table2 (You can call it whatever you want).
In LTRS set the Structure Template to your ECC View.
Set the View for Initial Load and View for Replication to your ECC View.
Change Refresh Behavior to No Action. (this only needs to be done on one.
Then do the same thing above for the other table in your view.
Then start the replication for both tables.
Once the tables show up under the "Data Transfer Monitor" tab in LTRC, click the Change Pencil button. Change the Transfer Behavior to 3. What this does is update a record even if the Operation Flag is Insert. Since you have SLT running for 2 tables, you will often have situations during the initial load where the record already exists. You MIGHT get away with this if you left the Refresh Behavior as Default. But I'm not certain whether it would work or not.
Anyway, it's something to try.