Do it. I don't think it's going to be hard at least the wood part. I have not seen plans but have seen projects and fliers. I have thought of a fixed gear Falco to try and simplify but gear going up is so cool.
There is an active yahoo group - GP-4_Homebuilt_Aircraft_Builders_Flyers.
There is a wealth of info in this group, as there is input from current builders and those who ahve completed and flying their GP4's.
I am currently building a GP4 in Australia.