I would like a flag-out system that i could pull back in and relaunch without
all my lines getting tangled ; does that exist ?
If you do a proper bar recovery procedure, you should be fine. Done it a gazillion times with my students, and it usually works like a charm.
For anyone not knowing what i mean by that, here below is what I teach my students. You can and should practice this. It can be done dry, with kite landed, the first time. If you have doubts, ask certified instructor or someone you know has this knowledge.
Bar recovery procedure
For one front line flag or Y mini 5th system (flag system should have stopper ball):
After you released the bar, and you are ready to recover and relaunch, approach the bar by pulling the flag/5th line with your hands ON TOP of the line (so you can let it go in case something happens, without risk of burning or getting snagged). Do not collect the line, just let it pass you floating.
Once at the bar, do not go for the CL. Hold on tight to the flag/5th line w one hand and grab preferred bar end (no matter what side). Begin rolling flag/5th line around bar end to lock. Best is to wind all flag/5th line until leash attachments, less risk of getting legs tangled, especially if in deep water. When all line is rolled, attach with half hitch. Now you have your bar, the kite is flagged and the flag/5th line is secure and the kite wont power up.
Now, one option is to roll all lines on bar like when packing to securely approach kite for self rescue or packdown. You reach the kite with a tidy bar, no lines hanging around or anything.
Other option is now to reset chicken loop and connect it to your harness. Then undo the half hitches on the flag/5th line. Start unrolling until only a few turns are left on the bar. Pause here and check if kite looks good. If so, undo the last turns, hold on tight to flag/5th line.
Let go of bar, grab safety release on CL, release the flag/5th line completely. Dont let the line drag through your hands, don't hinder the line, just let the kite pull the line through in its own pace. If you hold on to the flag/5th line during this, it might cause the kite to behave strangely. Keep you hand on the safety release in case something happens, and look at the kite.
This should reset your kite to relaunchable position in a safe and tangle free manor. If something happens, pull safety again and redo procedure if possible.
Remember, even if lines happen to be inverted (steering lines run through middle of front lines) the kite can still function and fly thus take you back to the beach. Just take it easy, no big moves.