My standard joke (from a very dark sense of humor) is you can sleep at least a dozen in the teardrop - you just have to chop them up really small.
The only "true" teardrop that sleeps 4 that I know of, that is well known, is the 560. The kids would still have to be small, but I imagine by the time the kids get large enough they wouldn't fit in the bunks, they wont really want to sleep with Mom and Dad any more anyway. Likely they will have moved to their own tent. And, CI now offers a roof-top tent option

. So, something to think about.
A google search will return a few others, obviously influenced by CampInn. I"ve never seen one in the wild, for my money, stick with the original. CI's workmanship is amazing. I bought a 2012, sold it, regretted it, and just ordered a replacement. They resell incredibly fast and at high prices. Look in the "buy/sell" forums. They don't last long. Just look at what sells the fastest to help you option yours out. I think there are some options which really aren't options...AC for example. Even if you won't need it where you are, there are people (like me) who wouldn't even consider NOT having one.
The pseudo teardrops (I'm sorry, a T@B or other Standee's) are NOT teardrops. They are just smaller trailers who are trying to capture the "fad" that started in the early 2010's. With the exception of a very few custom builders (ahem) they are all built using the same technology that is used throughout the RV industry. RUN. If you see gel-coat walls, its a dead giveaway. Elkhart produces self-distructing money pits. The materials are cheap, and it's clear that the people who design them are building to a price-point, and in many cases the spaces are not really thought out well. The designers are paid...no passionate.
If you want 4 adults. You're probably out of luck....unless you to full custom. I know one person who used to build custom teardrops, and his work was very good. Hs name is Dan, and he's one of the chapter leaders for "Tearjerkers" But I think he retired from the business. I would check over in the "TNTTT" midwest/hoosier chapter.
One of the most interesting self-built that I have ever seen is a pair. They tow in tandem...so Truck towing a teardrop, with a smaller tear drop behind. I can't speak for legality or safety. The smaller of the two didn't have a gally, it was just a sleeping quarters. When set up, it sat next to the "mothership" with a canvas and wood bridge between the two. Really beautifully built...stained glass windows...stunning actually. A lot of creativity want in. Because it was a tandem trailer, there were some states they couldn't drive through. But Indiana allowed it then, ymmv.
Study beofre you built - my only advise is to learn a lot about saving weight...it adds up surprisingly fast.