Re: Electronics overkill?
Define your 'lengthy cruise'... both in duration and intended destinations. In many area's I'd suggest that radar is not a necessity, nor is GPS however it's a major convenience. I think radio and depth sounder are the basic minimum, a knotmeter is nice to have too for sail trim. I think wind instruments are another 'nice to have' but certainly not necessary.
But there's no denying the convenience of having a plotter screen with your position shown to you.. the risk, of course, is getting too complacent with it all...
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)