If I use my vehicle for multiple business lines, can I deduct the actual expense for one business line and take the standard deduction for a separate business line?

You can.  However, you can only depreciate (actual expense method) the vehicle for one business.  It will be crucial to have kept good records on the usage of this vehicle.

The expenses have to be allocated to each business; no double deductions are allowed.  If one business uses the truck 80% of the time then it would get 80% of the total business-related vehicle expenses. Once again bookkeeping and proper records play a major role in determining the split.

If you already have used the Actual expenses method, you must continue to use it for that business.