this might help:

I got the 1870 for flat water paddle up. My struggle. However, I have used it in super light wind parawinging twice now. Since I am still trying fly the foil off flat water paddle so I decide to use it in really light wind and small swell to get the feel of foil and foil box placement. Worked great, turned intuitively , slow speed 15-16 mph max but fine. Fun actually Used with a med fuse, 158 stab, big kt dragonfly2 . 5m pocket rocket 2 and at 90 kg I can pop up in minimal breeze and swell. The wing tips are rounded so there is less to stab you with wide span. So nice to have pump foil flat water sup foil and light wind parawing foil all in one.

Sounds promising,what wind strength was it when you PWgd your 5m & kanga 1870.I also have invested in a K 1870.