Cheapskate
Seriously, I hear you.
Get an older 97-2006 4cyl Camry, get you about 30mpg on the way there with out feeling like a sardine. And get an older truck with a AGM battery or battery saver to park at the lake.
Nothing that can pull your Tsunami is gonna get high 20s. At least not available in the USA. Love to have a Dakota sized truck with a Cummins BT4. That would be perfect.
I think an old Dodge 2500 '93-'97.5 with the 2 gen 5.9L Cummins would be a good single vehicle choice. To this day nothing will pull better or more economically. Maybe a CNG powered work truck but not sure how available they are up there or if filling stations are adequately located.