Let me start by saying that I am partial to the Sportsman, having built one myself. However, the numbers you mention from KITPLANES are unrealistic. The kit price for the Sportsman with shipping is about $55K. There is no way you are going to get one flying for $75K unless you steal the engine and prop and have no radios. A good general rule of thumb is to take the kit price and triple it for a complete airplane. For $55K x 3 ($165K) you can have a nice airplane with a new engine and some decent radios. You can build for less but you will get less. With the IO-390 engine you can easily cruise at 145 knots (167 mph). That makes a trip of 3-400 nm each way a reasonable weekend jaunt. It also gives you a plane that can land on a 1200 foot grass strip fairly easily.
You will have to decide what you are comfortable with as far as how far you fly in one day. If I am trying to cover a lot of ground I will fly 6 to 8 hours in day. Some people will push that to 12 hours per day, but I find that way too tiring. Some of it depends on weather. Four or five hours of hard IFR or rough turbulence will pretty much wear anyone out, but a clear smooth day will let you do much more.
Appleton to Boston is definitely doable in one day, but I don't think that round trip in a weekend is a reasonable thing to do. It just doesn't leave you any time for being in Boston. However, you can make that decision for yourself.
I think that two planes is also something you should really think long and hard about. That is a lot more insurance and hangar costs, and more time spent doing maintenance. I suggest you focus on one plane that meets 90% of your needs, get that done, and then see what you want to do from there.