Alex, we have no experience here with the bags you are talking about. A friend used some kind of special paint for tanks. Also you could get the tanks galvanized but there is always a risk that it collapses in the heat if the vapor holes are too small (filling and gauge).
You should definitely visit Lesany once you are in CZ, it is army run, much bigger and much more to see than in Kraliky and Rokycany. Its also said to be the only place outside Israel where you can see a Merkava tank. During the Tank Days you can see it running. Also there is a newly restored pre-war Skoda LT vz.35 tank, the only running in the World. The admission is free.
http://www.vhu.cz/english-summary/
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Czechoslovak Army 1915-1945. Czechoslovak Independent Armored Brigade Group in Great Britain, Czechoslovak Army in Middle East.
1938 Standard Flying 12 Staff Car
1943? Ford FGT cab.13 project
180 gall WWII water bowser project
1942 Fordson WOT8 project
www.rotanazdar.cz 