RC-300- Multiple Time signature on BOSS RC300

[PGmusic]

Hi!

I'm pretty new on this kind of forum, but I see a lot of useful info!
I'm a pianist and composer and I'm diving into the loop-stations world with my BOSS RC-300. I'm interested in creating multilayered music. Perhaps with the example and the result I aim, it will be easier for you all to understand.
In this particular piece on which I'm working I would like to achieve:

Track 1: measure in 7/4 (as base)

Track 2: measure in 7/4 (additional material)

Track 3: measure in 5/4, which is repeated 7 times to meet again with the downbeat of the 7/4 measure of Tr1 and Tr2.

I'm not working with the internal drum machine of the BOSS rc-300, I do everything on the piano. I tried to unlock some feature of the track's settings (f.i. 'loop sync off'). So far the only way to do what I want is to have 'loop sync off' AND 'tempo sync off' on all the three tracks... but if my timing in playing is not perfect the whole sounds is getting very messy.
Any other opinion?
 Thanks in advance for the feedback.
Cheers!