I would get a helix 5 with a power cord off ebay and the proper map chip for it. The wing dams have been there for years so even a used old version of the map chip should work well. I cannot see spending more than 250 bucks total if you went the used route. Ebay has head units for pretty cheep often times.
From what I can see, any Helix 5 with GPS wouldn’t even need the map chip as the preloaded maps show wingdams and such?
If any IDOers are selling a unit with GPS that fits my need, let me know. Spending ~$350+ for a small new unit that does this seems pointless if a used one would do the same.