Casual or ranked, it's still PVP since you still get rewards from it. I only do ranked PVP to get the tier rewards and then I stop. I test it on an alternate account
I don't sit there and play all day to gain level after level where it looks suspicious. If you got to 100 in a day or so, that's definitely going to stick out.
Also beware about joining an existing guild. Members will report you if your stats are too high. Have been playing on an alt account for almost 5 weeks now.
Also...it's possible to get to level 100+ without the use of the mod.