Yo Rate1
re :"As I understand the big different comes from that Solartex has glue applied to it compared to Koverall. Allthogh finer weave and taking less paint, but still twice the weight!!! What about using silk, could that be an alternative, or a combination of silk (over sheeted areas if not fiberglassed) and Koverall/Solartex over the fuz? "

I would suggest that the weights quoted for koverall are as it comes out of the packet rather than finished...you still need to stick it to the framework and then "seal with 1-2 coates of nitrate dope" (see http://www.sigmfg.com/IndexText/SIGKV001.html ). Methinks this would then get you to the state that Solartex comes to you except for the overqall glue coverage. This comment does need checking out though 'cos I've never used koverall in anger. This website makes reference to silk covering.....nothing further that I can add except for my limited experience of the stuff which seemed to promote the "starved horse" look on covered open bay structures.

Tails look good btw

Cheers