hi odot
i did have a similar problem years ago and been shoting instax ever since.
the convenience(price and availability) was a big factor and since 2 years there is a bw option too
if you want to shoot wide or square in a better way look at what option8 is doing with conbersions or try the instakon from mont camera. for instax square there is a lovely system form ninmlab
https://www.ninmlab.com/ , i have the back for a nikon fm2 but they have it for a variety of brands
hope this helps