RE: 45cm skinny extension? available?
A third (expensive) option is the Liberty carbon extension (with STreamlined pully). I had mine since 2001 and regularly sail it extended above the 40cm level. Still holds up just nice.
The Hot Sails Maui extension is measured from the pulley and up which means that they offer "real extension" SOm brand measure the actual piece of tube and then you have to guess how much they actually extend. This holds for Liberty, so you have to subtract about 2cm from their advertised length.