Leeon did design a trapezoidal wing tip extension. I am working on getting this drawing to add to the existing drawing set. As for any other extension, Leeon recommended a maximum of 9” per wing.
Build time for this or any other design is highly subjective and dependent on the skills and knowledge of the individual builder. That said, comparatively speaking the DA-2 is much more simple to build than most aircraft in it’s category.
No. In order to qualify as an LSA the aircraft must stall clean at no more than 51 mph. The primary reason for the high stall on the DA-2 (60mph) is the high wing loading which makes for a nice stable good performing aircraft but does not work for lower stall speeds. In order to reduce the stall speed we would need to increase the wing area which in turn requires re-engineering of all the structural components of the wing and attachments.
There is not any other options for the landing gear, but this is experimental aviation!
I am not sure of the motor mount for the VW engine. The motor mount in the drawings is for the small Continental engines. If the VW accessory case uses the same pattern then I would think it will work without modification.
The G limits were never stated which would make for an assumption of using the Normal category limits.
I do have plans for a removable/folding wing option. I need to work on this to clean it up and make it presentable. I also plan, in the future, to come up with a simple folding wing design that can be done by one person with no tools in a very short amount of time.