1 mpg = ouch - lower speed (like rowing) would equal ?
I'm used to Bowriders

And with one of those you're pushing a lot less weight through the
water. Typical cruisers are upwards of 10,000 pounds and moving that
requires a lot of energy. You really have to decide if you want the
added space and amenities. You have to juggle all the variables.

Survey is 4 sure

It's always a challenge finding a decent surveyor, and then getting a
thorough inspection done. Be sure to find a reputable one that's done
boats of that make, or at least style.