Jon's words are well crafted and spot on. I would add that you should build in plenty of cushion on those tow ratings. For example, my trailer (Casita Liberty Deluxe) has a 'spec' dry weight
around 2500 lbs, but we are every bit of the 3500 max axle
rating when loaded. I am currently seeking a tow vehicle with at least a 5,000 lb rating for cushion in the mountains. If your Cherokee is a newer one, then it is front drive, and has greatly reduced towing capacity over the older ones due to independent rear suspension (instead of a full axle
in the rear). That is not a deal breaker, as many people successfully pull with the independent setup. I found in my vehicle (Honda Pilot) that the rear wheels wear unevenly due to splaying out slightly.
As one who traveled with a big dog (but not in our little trailer), there is a lot to think of there. Bed space doubles as seat space and storage sometimes, so preserving a spot for your boy can be difficult. If he likes the sensation of being crated, some of the Casita
models have a 'tunnel' of sorts under the bed that might work perfect.
I would also mention price. It is very easy to get sticker shock and run away to the 'stick built' trailers (pretty much every trailer on the market except for molded fiberglass models or Airstream). I encourage you to look at prices on 10 year old trailers. "Egg Campers" and Airstreams generally still bring 70-80% of their original selling price if they are well cared for. There is a reason: Most every stick built trailer WILL leak at some point due to the manner of construction, but it is nearly impossible to leak in any serious way in the egg campers. They are quirky, but extremely well built and last a very long time.
It's a little weird going through the shopping process, because much of it is contrary to the conventional way (going to an RV dealer, or cruising classified websites). First, I would review all the floorplans online, and narrow the field to 3 or 4 choices. Then use the referral programs through the manufacturers. To see the specific model you are interested in. It took about 20 minutes to be in touch with a local gent who had exactly the model I was interested in, and he was happy to show me his trailer (since he would get a check if I ultimately ordered a new one). That way you can narrow your choices down even more. Once you know what you want, you can narrow your search for that specific one.
I got very frustrated with the pile of fake ads on Craigslist. There is a golden rule: If it seems really cheap, then it is fake. Egg owners know what they have, and anything below 6,000 is likely a fake ad from some kid in Nigeria. Other tell-tale signs are pLayINg %wIth* CaPs to fool the robots searching for this sort of violation.
Keep in mind that it is incredibly rare to find a egg camper
at an RV dealer. There are a couple dealers near the factory in Texas (Casita) that try to keep one or two around, but it is generally a dealerless society. Don't let that worry you. The online community is among the best I've seen and incredibly helpful. For example, you can usually find someone willing to go look at a camper for you at some distant locale. If you have a break down, there is usually someone nearby to come help.
My experience followed Jon's advice - Be prepared to buy. Have your money in order, know exactly what you want, and be prepared to travel quickly to go see it. I literally had 3 or 4 bought out from under me in mere hours after the ads hit the net. Ultimately, after about 2 months frustration, I had 3 of my exact model go up for sale
on the same day, all within 2 hours of me. I took off at sunrise to look at them, and by the end of the day had our perfect little 2003 Casita
Good luck in your search. If I can help in any way (N FL), please feel free to reach out.