definetly accept credit cards at each show. not sure how things are in your area, but in mine the acceptance of credit cards is a must as for solving your delimena, why not order another credit card imprinter off of ebay. i beleive they are no more than 20 bucks (its been a long while) then that way everything looks more professional with the imprint...IMO as for the legality of writing everything out, not sure if there is law stating that you cannot do this, i am sure there isn't. this is doable but will be time consuming.