Even if it is "decent red filter quality" modern films are panchromatic AND faster than films when those were designed. The backing paper is enough for briefer exposure with most films but I agree, cover with tape. I have a Kodak..heck, forget the model but it's a box camera masquerading as a TLR with a faux viewing lens that's really just a viewfinder. It's a nice condition old class my wife, then g.f. bought me and takes 620 film. It's the only red window camera I have and I use it mainly for novelty interest, but I do tape it over when I put it away with film in it.