Thank you for your question and pictures. Unfortunately, I believe you are correct in diagnosing basal canker in your maple tree. The symptoms of this fungus show up in the base of the tree with loose bark and in the canopy with reduced leaves like you describe. Here is a publication from Wisconsin Extension:

https://kenosha.extension.wisc.edu/files/2020/09/Maple-Decline-A2532.pdf

Also, you have a crack in the bark that runs up your tree. I'm not sure when you noticed this, but basal canker can cause this, and also at one time in the 30 years of the tree it could have encountered sunscald or frost crack in the winter. Here is more information:

https://extension.umn.edu/planting-and-growing-guides/protecting-trees-and-shrubs-winter#sunscald-1263860

Since your tree is older, I think you should get a professional opinion since basal canker may be controlled in younger trees. To find a certified arborist in your area, here is a link:

https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional