I have a 2018 Miramar 35.3 and there are no gutters and downspouts.
I have the 3m j channel which I am going to install but I am not sure how to attach the gutters can anyone advise how you have done it?
I ended up putting the gutters around the windows.
Let it sit in the sun to heat up so it's more flexible .
Make sure the were you install it is clean ( rubbing alchola or etc.)
After pushing it on with my finger I used a tooth brush handle end in the channel to make sure it fastened.
Also do a search on YouTube there are some videos.
Hope this help
My coach has side spouts at all corners but they are only about 1 inch long. I have a friend with a 3D printer and weíve talked about how easy it would be to make extensions that could just glue to the short ones. 3D printing is amazing and Iíve used it to make several handy products.