I haven’t but we were camping when it was really hot and the people with tent boxes looked very, very unhappy and the DDogs looked even sadder.
I think it was because they were in an exposed field with no shade.
We go camping and the things I like about it are that we have enough room to sit inside if it’s raining or cold. Evenings often revolve around card games, snacks and the odd drink of wine.
We pitch the tent at the beginning of the trip and that’s it, you just go to your bedroom when you’re ready.
You leave the tent where it is during the day and don’t have to pack anything up when you go out.
I would ask him what he thinks the advantages of a tent boxes are and maybe have a look at one or two before buying. We saw a couple recently and I’m not claustrophobic but they were very small inside., literally just a bed with nowhere to store your food, cool box, clothes, shoes and all the other paraphernalia you usually take with you.