Greetings, and welcome to RP!
Since you mention both Dance of the Dead and the impression that Moon Guard isn’t a place to go for Horde RP, know (if you don’t already) that Dance of the Dead is hosted on Moon Guard and that many of its organizers are Moon Guard players and guilds. My impression as an outsider looking in is that Moon Guard’s Horde population is smaller than that of Wyrmrest Accord, but not less active; there are fewer options for guilds, but the options that are there are in several cases thriving and quite well developed, and one of them might be the right one for you. It’s worth it to look!
As it comes to Wyrmrest Accord, though:
We have lots of guilds that post on the forums and/or check here for guild seekers, but we have lots of other guilds that don’t. To maximize your search pool, I recommend attending the Wyrmrest Accord Horde Guild Faire, which usually takes place on the last Sunday of the month. The next one is scheduled for October 29th, and it looks like it’ll be held in the Drag in Orgrimmar, which is its usual location (but occasionally it’s held elsewhere). You can find a link to the guild faire’s Discord server on their Carrd page here: https://hordeguildfaire.carrd.co
If you’re into Discords, then I also recommend the Wyrmrest Community Project for helping you get into the swing of things. The WCP is not Horde-specific, and it’s also not guild-seeking-specific; however, it’s a great place for networking and for catching wind of public events, which are themselves a great way to get engaged in RP, meet new people, and get to know potential guilds (and let them get to know you).
Good luck! I hope you find exactly the kind of guild you’re looking for, and I hope you enjoy the search as well.