Rake cover

I live in arizona and a reputable roofer isn’t available for two weeks and we get rain regularly.
I had a rake cover(?) break off exposing the underneath near the upside down v .I am using old fashioned duct tape and a trash bag to keep the rain out untill it’s fixed will this be o.k? http://www.roofing.com/images/topics/5739/img_1188520831.jpg

Post a picture if you can because I don’t think you know the correct terminology to convey your request properly.

Plastic sheds water; so done right, yes.

While I don’t happen to see any duct tape or a trash bag in his pic, I think he means (by the photo) a ridge cap.

Given the pitch, unless there is a physical limitation I don’t see why he can’t get one from a local supply source & attempt the installation himself.