I can't say for sure - but I'm pretty sure the LATCH systems are fairly limited in terms of max weight. They're super easy to install but only applicable for the first year or so - the car seat manufacturers recommend starting off using the actual belt just to avoid having to redo it down the road.
For really little ones, the UppaBaby Mesa has a LATCH base that ratchets and is a breeze to install.
I originally purchased a Clek Foonf for my Model 3 and found that while it is more narrow than most, it is also taller than most (the entire thing including the sides) so lifting the baby over the edge and into the seat was more difficult. We moved it to my wife's Range Rover, which has a much taller door opening and it hasn't been an issue since. I ended up getting a Nuna Rava for my Model 3 and have been happy with it. It is wider than the Foonf and requires a little care when folding down the split rear seat to avoid scuffing/hanging up on it - but it's easier to load the baby.
Installing the Nuna is easy using the vehicle belt. You basically thread it through - pull the belt all the way so it goes into lock mode - let it retract on its own - and then press down a panel on the car seat that automatically adds the appropriate amount of tension. Not a ratchet system but just as easy in my opinion. Threading it is the only annoying part because you have to go through the cup holder holes - which leaves the cup holder partially sticking out after installed.