IMHO the Axxera radios make great boat anchors. I replaced mine a long time go with the Pioneer AVH-4100NEX. There are newer models now. The display includes reticulated lines so that it is easier to judge the rear camera distances. The Pioneer NEX series have Apple CarPlay which I use all the time.
As for "on board" vs. a Garmin GPS, I went with the Garmin RV 760 GPS. I have it mounted on the dash above the instruments. I like it there because it gives me a speedometer without taking my eyes off the road. It allows you to put in length, width, height, and GVWR. It has never gotten me in a bad situation. The other thing I like is the lifetime updates.
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