I asked Kitfox what was the difference between a 5 and a 7 and they said not much. The 5 is approved by LAA. You could try talking to LAA engineering.
The 4 with 1200 lbs AUW is quite a competent aircraft and is approved and is still available.
I used to share a 3 with a 912 but I did fly a lighter 4 (early 4s did not have the 1200 lb AUW). The 4 handled more like a light aircraft than the 3.