The 23-year-old Lakers star is getting some well-deserved R&R before the All-Star break ends ... taking a boat trip in Miami with an insanely attractive model ... and cuppin' a handful of ass in the process.

Kuz -- who won the MVP of the Rising Stars Challenge this past weekend -- kept the winning going on Monday with rumored girlfriend Katya Elise Henry ... a model with nearly 6 million followers on IG.

The couple(?) have yet to acknowledge any real romance on social media ... but it doesn't take a genius to put 2 and 2 together with this one, thanks to Kuz's body art.

The rumors date back to last year when KEH was spotted attending Laker games ... and this pretty much closes the case.

On top of being ridiculously hot, Henry -- a Miami native -- is also a businesswoman with her own workout plan (including an 8-week "booty program") and bikini line.

No word on whether this is love or just young kids having fun ... but it's clear there are no losers here.