I checked my research. The original drawing doesn't give a hint of a stepping of bearding line is right for the cutter. So it's also possible to use the stepping line, as you did for your design. I couldn't find the reason, why I choosed a bearding line in the moment.
The foto shows a test-installement of the deadwood which I did a few years ago. It was build in the original way. For glueing the pieces together, I drilled 0.5 mm holes and use brass pins.
In fact, what you want to do is what we have been doing. In trying different processing methods and restoring the original structure to the greatest extent, I can provide the specifications of dead wood.
That's right, The easiest way is to change the way, you laminate the parts of the deadwood. For my idea it's not necessary to change the position of the frames or cant frames.
If I follow my old design the deadwood has a thickness of 4.2mm upper the stepping line and from 6mm under. This may vary by your design.
You can build each timber of the deadwood from 3 parts (as you always did), one center piece one for the port and one for the starbord side
1. Take a wood of 1mm thickness and cut the correct shape of the whole deadwood. On this the parts for the starbord and port side of the deadwood will be glued
2. Port side: take wood which is 2.5mm thick (half of the deadwood thicknes under the stepping line - half of the center plate). Cut the 4 pieces for the different parts of the deadwood and mill the part over the stepping of bearding line to the correct shape and thickness.
3. The prepared parts glue on the center plate (if possible make small markings in the center plate and the back side of the visible parts to make the positioning easier.
4. Repeat the steps 2 and 3 for the starbord side.
That's it. The model-builder must give the correct shape under the stepping line. If everyhing was done in the right way, the deadwood should look like similiar to the foto with a stepping instead of a bearding line.
Perhaps it is also possible to do this without the center piece, but then there is a marking necessary to glue the pieces nicely together. I don't know if you can mill both sides of a piece.