it can be done quite easily with a delayed start for single players, anymore than one is difficult. Delete any task that is not 320 points. Delete any that you cannot prepare and have ready to go eg don't save boats, animal, fishing, some don't even save trucks.
As your 320 tasks appear start stacking your machines withe the required items in the order you are going to complete tasks, you can take as long as you like. Once ALL your tasks are ready select your first task, in the order your machines are stacked, and you can complete 10 in under an hour, I have seen it done in 15 minutes without using diamonds.