Transportation charges not likely excludable from taxable price

We are a trailer dealer with a number of out-of-state customers. Our retail sales of the trailers are subject to Section 4051 excise tax. We generally transport our taxable trailers to out-of-state customers from our dealership. Our primary trailer manufacturer recently offered to transport the trailers directly to our customers located in certain states, because it is cheaper to ship the trailers to those customers than it is to ship the trailers to us. Under this arrangement, the manufacturer would invoice us and give us title to the customer-ordered trailer prior to its delivery. We would also enter into an agreement with our customers that provides for direct delivery from the manufacturer. If the manufacturer transports the trailers directly to the customer, can the transportation charges be excluded from the taxable price?