The tounge weight of the TT APT linked would be calculated by multiplying GVWR of 3,500 * 12% which gives you 420.
Add hitch receiver weight, weight of the occupants and stuff in the minivan. Pets?
I Googled payload 2014 Dodge Grand Caravan and got 1,567 to 1,729 lbs. That's how much your van can carry which is much less than its stated tow capacity. Look at the sticker in the drivers door jamb. Post a picture of it.
I have friends who just got out of the lifestyle because their towing experience got dangerous and scared them - were towing a smaller starcraft hybrid with a dodge minivan. No WDH because of the hitch class as mentioned above. IMO - not safe for a family, no matter how far your going.
Pop-up's do have bathrooms and slides. Look at Jayco.
Good luck.