As someone who lives in a city where it's exciting to break 60 kph (37 mph), what makes it so unsafe when you drive slower?
If traffic flow on a highway is faster than you by a good margin, people have to make aggressive lane changes to get around you, and you're basically an obstacle in traffic. Yes, it's legal, but you're being a jerk and it makes things rather unsafe around you. I'm quite familiar with this - I-25 between Albuquerque & Santa Fe is theoretically a 75mph road. Really, if you're going any slower than 75mph in the right lane, you're a hazard. You should be doing closer to 80, and traffic flow in the left lane is around 90.
75 should not be a problem for any well maintained vehicle.
"Can do" and "Can do without tanking your fuel mileage" are two different things. A lot of trucks are geared fairly low, and your fuel consumption gets stupid rapidly as you exceed 60-65mph. The truck can do 75 or 80, but it's not happy up there, and will burn a lot more fuel to do so than it does at 65. I'm fairly familiar with this, having a truck geared for towing.
No I hadn't really considered any changes but perhaps I could. My current truck is worth about 4k with 70k miles. A few leafs and Prius around, but the purchase price would set me back pretty substantially. Any 40 mpg cars for around 4-6k?
Geo Metro. Ford Festiva. Honda CRX. Pretty much any of the late 80s/early 90s tin cans will do it for your budget.
But, really, given the $2k savings in fuel, I'm not sure you'll make it up on purchasing a new vehicle.