Perhaps you've already aware of this, but what can be a big challenge
with 2-year-olds who are over 40lbs are carseats. Most carseats with
the built-in harness are only good to 40lbs. Most children that young
are not tall enough for booster seats. To be tall enough for a
booster seat the car seatbelt needs to go over his collarbone (not his
neck) and around his hips (not his belly). There are only a few
carseats that will accomodate kids of this age at this size, and for
the most part they're pretty pricey. Fisher Price and Britax make the
only ones I'm aware of.

Check out the law in your state as well, here in WA, the law states the
child has to be both 40lb AND 4years old to use a booster. There are a
lot more car seats on the market now that accomodate extremes in both
directions. Britax has a few, though all the ones that we saw were very
bulky, we have a small car and needed something smaller, we ended up
something called "Safeguard Go Portable Booster", which needs your car
to have a rear anchor, it looks like a booster, but as a soft back that
once anchored provides a head rest and the shoulder attachments for the
harness, which have a wide range of height adjustment, it will take a
child up to 60lb with the harness and converts to a booster and has a
strap to locate the seatbelt correctly in that mode. The other smaller
seat that we found was called Radian65, it doesn't convert to a booster,
but has a lot of potential for height adjustment as it does newborn to
65lb in a 5 point harness, there is also Radian80, which was a bit more
expensive, but goes up to 80lb, I don't know what other changes it has
compared to the 65. They are both very heavy seats, but a very different
shape to other seats on the market, they also fold, the seat folds up to
the back and lies flat, we decided to buy a bag so it can be carried
like a rucksack, but there is a single shoulder strap on the seat, the
shape of it has also meant it's a lot easier for our 2.5 year old to
climb into, which has been fantastic for me as I was struggling to get
her into her old seat and she couldn't manage herself. Unfortunately
we've found it quite a difficult seat to install and adjust, but it's
been worth it compared to the alternatives.

Cheers
Anne