Haulvoc

Technically you can use mods (the launcher will disable them when you go online), but if you're just setting up a profile for multiplayer, you shouldn't use mods. I recommend you use two profiles, one for single player (with mods) and a clean one for multiplayer. You're allowed to cheat to get money and/or experience for multiplayer. That's the quickest way to make a multiplayer-ready profile and you'll be able to buy and upgrade any truck or trailer you want.

You need separate profiles to stop this from happening. You can create a new promods profile for single player, or you can duplicate your current profile by following this guide: Otherwise the game will "think" you're loading your profile for the first time, which causes the long load times.