First of all, you need a drone with EMP, preferably level 2 or 3. Also, you must have the grenade launcher skill and the appropriate weapon. In principle, the whole operation can be done without these abilities, but the process will be more complicated and time-consuming.
Go to the Villa Verde Alpha Rally Point in the Villa Verde region in solo mode (co-op will not work). Once there, open the map and find the nearest "+5000" resource convoy east of Villa Verde Alpha. Mark it and the next control point on the map. Then take the motorcycle and quickly get to the marked checkpoint.
Drive across the river and park at the end of a fork in the road, hiding behind trees. Quickly switch your weapon to the grenade launcher and use the EMP drone. Stop the convoy with the drone, making sure the enemies won't spot it. Then shoot three grenades at the first and last cars to detonate them. Run up to the middle car and kill the passenger and driver. Mark consumables to complete the side mission and gain 5000 resources. If done correctly, all enemies will be dead and you can quickly return to the Villa Verde Alpha rally point. Since you are in single player mode, the world will reboot and the supply convoy will rebuild. Repeat this process as many times as needed to get an infinite amount of resources. Each time, the entire process should take from 1:45 to 2 minutes. You can get from 150 to 000 resources per hour, depending on your efficiency.
Note: Be sure to meet the convoy at the fork in the road. If you meet them further along the road, there is a base nearby, where enemies will continue to revive and hunt you until you leave, which will drag out the whole process.
