Becquerel method isn't nearly as dangerous as the traditional mercury method, but elemental iodine can still cauterize your lungs or blind you. To be clear, making Daguerreotypes is very expensive, about $65 for each finished 4x5" plate. Cutting corners will only make a difficult process more difficult. If you have any doubts try something easy and cheap, like wet-plate collodion... (some irony intended)