The WR36 Adriatico design looks good to my eye, and the plans price
also looks good.
Have you considered buying
the plans and building a balsa and cardboard model at a suitable scale? I did this before I brought Boracay and it crystallized my ideas of what I wanted and while Boracay is less than perfect she's still useful to me some 7 years later.
There are some aspect of DIY that you need to keep in mind. You need a building space that the boat can be moved to a launch site from that is available for at least the estimated building time, you need a job that provides the required income
and you need a very understanding significant other.
In particular you need to find the hours to build. I built a 32' ferro
and a 21.5' ply from scratch and the WR26 looks to be bigger than both. My limited experience suggests that you'll be looking at more than 6 years from start to launch, with time to completion even longer. Building a model first may shorten this. If you have commitments that will keep you in one place for the anticipated building time then a big project
may be feasible.
Some serious costing is also in order. Draw up a list of materials and equipment
and cost it. Smaller engines may also help.
I'd also strongly recommend power only (trawler cat?), unless you have a dream of sailing.