There are only minor changes between the 587 and new 588. Furuno is suppose to be the benchmark of fish finder tech, probably cant go wrong with it and a 600w or 1kw transducer.
587 with 600w transducer (1kw if budget allows),
Elie 5 as GPS
navionics on a tablet (most people have one these days) mounted on a Ebay stand as a backup
Is a pretty usable setup.
If you pass up on the 587 let me know as I will take it. My 582L just shit itself and they share the same plugs