One could argue that the whole point of a proper roleplaying guild is to create a specific concept that in its nature includes one form of concept and excludes the rest. If a roleplaying guild doesn’t stand on its own as something unique in terms of conceptual workings and restrictions on what is and isn’t allowed, it shouldn’t really be a roleplaying guild at all.
It sounds to me that you’re looking for an umbrella roleplaying guild that is in essence conceptless, and just serving as a “hub” for roleplayers of all kinds to gather. Try “Warcraft” for an instance, I know they have advertised as a partial roleplaying guild. Your only other choice is to find a roleplaying guild that caters to a concept that includes your own character, or to remain guildless or in an OOC guild.