Been van shopping lately.
I can find an Chevy Expess 3500 12 passenger van with the 6.0 V-8, or a 15 passenger Ford E-350 with 5.4 V-8, 20,000 to 40,000 miles, for less than the price of a Grand Caravan or Town & Country with 50,000 to 60,000 miles. The 15-passenger Express 3500 runs $2000-4000 higher in this area, as it is the most desirable extended length passenger van.
All of these are 2012 or 2013 model year, coming off short lease or from rental fleets. Part of the reason these full size vans are lower cost is they are pretty basic on acessories, where minivans are ordered for fleets with midrange or upper midrange trim, $8000 to $10000 over basic models which are impossible to find, new or used.
Minivan is going to tow a 3500 pound low profile trailer at most, if it has factory tow package. Very few do.
E-350 V-8 will tow at least 7000 pounds, full TT frontal area (the V-10 takes that to 9000 or 10,000 but you don't find that one coming out of rental). Express 3500 with 6.0 will have similar towing capacity, between Ford V-8 and V-10. Towing package on these full size vans is. just wiring and hitch receiver. On the minivans tow package includes drivetrain and suspension upgrades to make what is basically a roomy car behave a little more like a truck.
If you don't need 12-15 seats, everything behind the front rom is easily removable, adjusted carge space vs seating to match your needs.
Expect the full size vans to use 50% more gas when not towing. When towing, fuel use depends more on the size of the trailer than the size of the tow vehicle.
I keep thinking, yes I could use a minivan (my car is a mini minivan, Honda Fit) but when I look at the limited capabilites, vs economics of going full size on the van, full size just works better if you want to tow something.
I have two friends who pull small egg trailers (one a Scamp, other a Casita) with minivans. It works because they travel alone with minimal loads in the van. Put two to four adults, two car seat kids, into a minivan and it is fully loaded, if not overloaded, before you add the hitch weight of the smallest travel trailer. For as many people as you want to carry while towing, not only do you want a full size van, you want it as a one-ton, e.g. 350 or 3500 series, not 150 or 1500. Although E-150 is now using the frame of the E-350, and same. size tires, other suspension parts are downsized for a somewhat lighter load.