I've built a handful of these YAK's from DTFB. I don't think I scaled it it all - but I did make a template with card stock 1st - that way I could fit the wing on a single sheet of DTFB at an angle.
https://www.rcgroups.com/forums/showthread.php?964237-EPPYak55-build-guide-videos-free-plans
I also have a small fleet of 3D EPP and EPO profiles, and from building those, I think I have some ideas for a profile DTFB "upgrade" since most guys use Depron.
If I remember correctly, the best flying version of the above that I tossed togethor was:
1 - doubled up fuselage. basically make 2, glue them together.
2 - single sheet wing / horizontal fuze with a CF strip and covered in packing tape.
3 - extended servo arms for the aileron servo
4 - Carbon fiber servo linkages (although a "pull-pull" for the tail would work)
With the 2x Fuze and 1x wing you can use an X-type motor mount like these.
https://www.banggood.com/10PCS-X-Ty...-p-1090113.html?rmmds=search&cur_warehouse=CN