Heres the engine mount plates that come with the kit.. They are made of good 3mm plywood with what looks like 200 gram carbon cloth that has been vac bagged to each side.
With the 2 glued together I reckon they are more than strong enough to handle the YS on a bad day , so decided to lighten the bottom plate.. It saved 24grams weight savings and still feels plenty strong..

I I glued the two plates together with 24hr Araldite glue which has a very strong bond ..