Vikings have been operated at over their civil max weight for some time (based on what justification?), and so would probably be difficult to transfer to the civil register. I believe a civil G103 has a life of 12,000 hours, with major inspections every 3,000. However a Viking has a life of only 27,000 launches (again based on what justification?) - perhaps only 2,500 hours. I'm guessing most Vikings are around the 2,000 hour mark? The question to ask is why have the differences to the civil certification been approved?
Before the G-Register there was a BGA weight concession of +3% for non aerobatic flying. Did they fly over that concession weight? BGA gliders carried the concession onto the G-Reg but (for example) German K13s don't which means a porky instructor and porky student are probably over the placarded weight.
Are you absolutely sure it's the actual Vikings that have the launch limitation, or was it the hook? Got any documentation backing that up? It's a totally bizarre requirement if it's true.
Tost release hooks need an overhaul every 10,000 actuations which is less than ever 10,000 flights depending on how the actuations are counted. 5 per flight is common - 3 checks (back release, free drop, release under tension) plus 1 for launch and the release at the end of the launch.
http://wingsandwheels.com/media/wysi...lisch_2001.pdf
A life of 27,000 launches when the primary use is circuits off a winch is not very long at all. The average flight time for one of our K21s, at a hill soaring site, is 15.62 minutes. At a non-hill soaring site I would expect it to be less.