how does one stop their sandwich from going soggy once the presence of tomatoes is made felt?

after several days of soggy barms I have taken the decision to slice the tomato and wrap it in clingfilm with the view to making a more timely addition to the sandwich - however, this strikes me as a bit sex offendery

the other option i considered was placing a folded up piece of kitchen paper in the middle of the sandwich - however, this appears to my mind to be the action of a madman

your earliest advices would be most appreciated.

Regards