It for sure can be done, but validation by procedure qualification may be wise depending on the geometry and service of the part, as well as the function of the trailing shield.
We did this with knife edge airseals (GTAW with trailing shield) On some airseals we did more than 10 continuous build-up passes with only the trailing shield.... But this was done with PQR's and in partnership and with approval approval from the OEM.
The president of this company, Precision Welding Technologies: PWT oversaw the design of the trailing shields I'm discussing and sells them as well as consulting services for folks breaking into new areas
www.pwt-online.com/
If you contact them, tell Gregg that Larry from United sent you.