The full displacement sailboat with a small diesel is usually more fuel efficient than a huge trawler which might consume $20,000 worth of fuel on the loop vs about $5,000 in the sailboat.
As far as safety, for a large portion of the loop you are like 1/2 mile to shore or closer. Far different from a 5000 mile Pacific crossing. Probably you are never even out of cell tower range lol.
The downside to a sailboat are the bridges around Chicago but people seem to have their mast removed by a yard and they carry it with them through this part then have it stepped.
We have quite a bit of experience sailing, both our little 17 foot Montgomery and some weeks of classes of blue water sailing on a 42 foot (Beneteau iirc). We also used to rent a 25 foot Catalina before we got our 17 foot trailerable boat from a club in the Sound. 32 sounds about right for the shallow rivers and such. A 42 foot sailboat would make me a tad uncomfortable right now.
You have the right background hanging out on small boats to do this trip very economically. I would not, however, base your vessel decision on fuel costs as the primary factor. Please do some reading around for opinions for this.
A quick back of the napkin delta shows that the loop is, generally, about 6000mi. 6000mi at 6knots = 1000 hours running time.
For a 32-ish foot sailboat burning 1/2gal/hr, 1000hrs = 500gal. At $4/gal, this is $2000 in fuel.
For the same trip in a
VERY roomy and comfy (by comparison) 32-35ft, heavy trawler burning very realistically 1.5gal/hr, 1000hrs = 1500gal. At $4/gal, this is $6000 in fuel. Some can be better still than this.
If your entire year is costing $30-50K for fuel plus all other living expenses (dockage, eating out, activities, maintenance), this difference is small for the upgrade in comfort during a year long, once-in-lifetime trip, IMHO.
The right condition vessel, maintenance costs, comfort, safety, and air/water draft matters more so than fuel. Now, if you actually want to SAIL when you get down south to the keys/Bahamas, that's another thing. Your aren't going to do much sailing on the loop, tho. Again, MHO.
Read around the interwebs, though, and form your own opinions.