It's fine Tyger.
Discord has some considerations: there's levers to shut off parts of this, but Discord does track when you're online (on mobile and while gaming) which might rub RP users the wrong way. You can turn off the gaming tracking (finally, that happened mid-last year) and make it so Discord doesn't open on startup on your computer (so if you're doing something else you're not getting messages asking if you can make a move on RP when you're doing actual work.) But those tastes depend on the individual.
You can set up a Discord RP server similar to how The Cape Radio does their chat service... the invite code is public, but users come in with no rights and we get notified in a particular channel when someone joins. If we know who the username is (Paragon Chat is very useful for this purpose, or an alternate means of contact so you know who 'your' people are), we add them as a regular user role. If we don't, they stay unverified. It sounds mean, but it's a proactive defense as folks 'attack' other people's Discord servers by finding a channel no one is in and spamming content Discord bans servers over (essays about terrorism, things that 4Chan wouldn't blink over, etc.) Stonewalling unknown users stops most of that, at the price of needing more than one way to reach us costing us new users who don't care for that tactic. But for an RP group like yours, that might not be a bad tradeoff.
Last thing to consider: Direct Messages are DETACHED from Discord Servers. Like in City of Heroes, every user has a Global Name and a Server Nickname. In Direct Messages, you'd talk to someone's Global Name instead. If someone doesn't want to join your Discord Server (or doesn't get along with someone there), but wants to RP with you, you can make a Group Direct Message that persists (as long as the creating user doesn't leave the group, it stays around indefinitely). That way, you can still RP with them and not need to worry about the Server. Group Direct Messages is also a medium for more explicit stuff that has no attachment to your server, for example, if users want to do ERP but you have rules against it. Direct Messages is 100% policed by Discord, so your server has no responsibility if someone is abusing those groups (unless you're a member of a Group DM that's involved in a complaint).
The catch is everyone you do a Group DM with, you need to add them as friends. Without that, you can't join or host a group with them. This means they can see when you're online at the least (and what game you're playing at the most.)
Hope that helps.