Hot to installe multifoil TLX silver if 38x50mm are not available?

[Jonny Vee]

I have to install the TLX silver multifoil which specified to have 38mm thick batten but impossible to source on my area with only available in 25x50mm.

have you had any issues like that? How can this be solved? The 25mm is to thin and not enough air gap is left to let the multifoil work.

Thanks