If you're looking for a light wind kit, here is a simple answer to a simple question : best board for best sail and best sail range :
iSonic 110 : 7.8. Range 7.0 - 8.6
iSonic 117 : 8.6. Range 7.8 - 9.6
iSonic 127 : 9.6. Range 8.6 - 10.x
I have an iSonic 117 Wide and I can confirm that a 7.8 m2 sail is fine, even for my 65 kg light weight up to 18 kts of wind. So I'm sure that it would be no problems with 20 kg more body weight to keep her flying above chop at full speed.
I also doubt you can start and sustain the planing as of 10 knots with iSonic 110 + 7.8 sail combo for your 87 kg. I can do that on iSonic 117 Wide but I need an 8.6 sail. I need more wind for sure with a 7.7 sail.
So, if you really want to enjoy blasting in 10 knots winds, better look at iSonic 127 + 9.6 sail combo IMHO. Several of my 80-90 kg buddies are using that kind of kit and we are on par when doing drag racing as of 10 knots of steady wind despites our ±20 kg body weight difference. A 7.8 sail is definitely way too small in such light winds.