gps is useful for both trolling speed & waypoints. A lowend $100 gps handheld will do both, and you could use the handheld for hunting as well. Just need a 12v power supply/cord for all day use as batteries won't last all day in most cases from what i've read. I just bought a HH gps for trolling speed, but the waypoints are a + for me once I learn how, etc. I already had lowend ff's and didn't want to mess with replacing those as I am mostly understand their function/results, and live with it. I didn't want to complicate my fishing trips anymore than needed. Your pictures indicate you won't have secure storage for some of the high $$ electronics (I call $300 high $$ just because i would hate to lose it or be stolen, not because it would hurt me financially), so that should come into your decision process as well unless you do have secure storage for your boat.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.