I dont think this come and go strategy will sit well with most guilds, and you would need help from a guild to get started on a warrior when you hit 60 to get sht done before shadowlands. dungeon traffic is low now, and pugs will not take you without decent gear.
a warrior aiming for endgame is a big commitment, is very taxing in the gold department and faces heavy gear requirements and competition.
to me it sounds like you should stick with one level 60 char, and maybe a class that is easier to get going with, like a hunter or a mage.
those have good gold income and have access to gear with low competition in early tiers that will give you a powerspike in pvp and everyday use.
and what are you going to say to your guild? Goodbye for now, see you in some months? You said you want to play endgame with your warrior, I dont know if you really know what this means? It means that you need to commit in a guild and spend lot of time. Its not like you will pug mythic plus and wait for your weekly chest…