Tandem hydrofoil assisted catamaran upwash/downwash calculation?

Hello,

Design object is power hydrofoil assisted catamaran with tandem foil system. The foils are full length between the amas at keel depth or 1-2cm above it just for practical reasons. The shape of both foils is like HYSUCAT front foil.
I was searching on the net some info about tandem foils interaction, and found this empirical dependence:

L=1.95*V*sqrt(B/g)

L - length of wave hollow behind bow foil, m
V - speed, m/s
B - immersed span of bow foil, m
g - gravitational constant m/ss

As it turns out most of the successfull tandem hydrofoils of soviet and Rodriguez design were using this intentionaly or not to their advantage: the stern foil is at the upwash of the stream from front foil at cruise speed. And the most efficient designs have ~0.7-0.8L distance between the foils where the upwash is most beneficial, even if that epirical dependence was discovered about 30+ years later...

The questions of mine are:
1. This dependence seem to be very very simple. No dependence on the attack angle, sweep or chord of the front foil. Are there other formulas known?
2. Design specific interaction - how side amas which act as a big long endplate may change the wave hollow length?

Prof. Migeotte seem not to be on this forum anymore, but input from other hydrofoil gurus is very welcome.

Thank you.