finishing ridge on traditional garage slate roof (except for manfactured trusses)

I've tried to keep the garage i'm building as traditional as possible, but i'm struggling with the roof peak/ridge.
I've had to buy manufactured attic trusses for practical reasons. These finish at the top with a sharp peak.
They're erected and i've sheeted them with sarking boards (175mm X 14mm strips). 1F undertile felt is on, waiting on the slates (reclaimed if i can get them). I'll finish the top ridge with "zinc ridge" over the slates; the stuff which has a "bulb" and flat plates covering the top 6 inches or so of the slates on either side.
However, the felt sheet over the ridge is not in place because i'm struggling to figure out exactly how to finish it.
I've been given all sorts of advice, but the common theme seems to be that i need a "ridge pole" or "ridge bottle" running along the top of the trusses, inside the zinc ridge. This would usually sit on top of a ridge plate or something (probably a 3 inch horizontal seating at the top of a traditionally constructed timber roof) over the top of the final layer of felt.
I'm happy with this but i don't have the flat surface to rest the pole on.....
I've managed to source the pole, but i really need advice on how to finish off the top of the roof.
My thoughts were to bring the sarking boards right up to the top of the ridge with a straight cut on the side creating a small "V" where they meet at the top. I can then lay the final strip of felt over the ridge (kinda creating a bit of a dip in the new "V") and sit the ridge pole in this "V" securing it with screws and after the slates are in place put the zinc ridge on.
Alternatively, I can cut the top inch off of each truss peak and rest the ridge pole on this flat surface, but i'm not at all happy about the potential that this may invalidate the truss warranty.
Also, I can router a "V" in the bottom of the ridge pole and stop the sarking just short of the ridge so the pole rests on top of the trusses.
Please, does anyone have any experience of finishing a ridge line on a roof of this type with slates and zinc flashing.
Thanks all in advance Paul
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