There is no need to vent an oil. You should put a hard surface like coroplaste or foam core over a stretched canvas before putting the paper backing though. That way the canvas won't get poked from the backside.
Mat Framer this has been discussed and debunked both here and on HH. Those little holes are not so good for breathing as they are for breeding INSECTS ( roaches ,siver fish etc. also it is a great pace for dust and mould to accumulate.
I think the joking adage is "if it doesn't have LUNGS it doesn't need to breath"
do a search on the topic and insert Hugh Phibbs' Members' number.Also if you can go far enough back try checking out Orton's opinion .I was glad to see a recent reply he made maybe he'll refresh his reply for you.
If you want to know ALL about framing stretched canvas art, contact the Canadian Conservation Institute and get the "CCA Notes" on the subject. Also, the AIC brochure entitled "Caring for Your Paintings" is very good & concise.
One more reference: The PPFA specifications written by Merrill Grayson for the stretched-canvas section of the MCPF exam are excellent.