Since you cannot use Steam Workshop with the portable version, you need manual .scs mods. Here are the top 1.30-compatible mods:
The city of Milano was completely remade, and the entire northern part of Italy was refreshed to match the quality of modern DLCs. Euro Truck Simulator 2 1.30 Download PORTABLE
(not portable), you can get it through Steam by selecting the “temporary_1_30” beta branch. Since you cannot use Steam Workshop with the
To download Euro Truck Simulator 2 (ETS2) version 1.30 , the most reliable and legal method is using the Steam "Betas" Euro Truck Simulator 2 1.30 Download PORTABLE