How do I handle all the wires for a canless recessed light on 3-way circuit
Don't even try to run the 3-way switch leg through all the lamp boxes.
Bring power into the &quot;main&quot; or more accessible entrance - the one where you would want to put a smart switch.  Then, have a separate /3 cable that bypasses the lamps entirely and goes straight over to the other 3-way switch.
I have no idea why some sites recommend running the travelers through every intermediate light box... but this is very foolish for 2 reasons: #1 box fill, and #2 you would need /4 or /5 cable and they usually recommend using 2 cables instead, and that's a code violation.  (heck you're using 2 cables anyway, why not just have one bypass the lamps altogether?)
Then, from that switch, you send &quot;switched-hot&quot; and &quot;neutral&quot; onward to the lamps, and daisy-chain the lamps in the normal way.
Mark your wires correctly
I recommend sending always-hot to the far switch -- if you do that, you MUST use white for always-hot, and you  MUST re-mark both ends with black tape -- that's Code.  I recommend marking the other 2 wires with yellow tape to designate them as travelers -- that's not Code, but it will make things vastly easier to hook up and troubleshoot later.  (yellow = brass screws on the switches - get it? :)
If you're wiring it with travelers and switched-hot going to the far switch, you are not allowed to use white for switched-hot - Code again.  Use red for switched-hot.  Since you're using white as a non-neutral, you MUST mark it with a hot color - since you have to anyway, I recommend again yellow tape on both travelers.