Hi Sharon! Thanks for visiting planDisney.
Yes, you're correct that Disneyland Resort doesn't have a listed maximum weight for their convenient
rental strollers, which you'll find available for daily rental just outside Disneyland Park. Just one of the differences between park operations!
Your little one should be just fine within the single stroller, I think. I've got one about the same age, and he still rides on and off in the parks. Park days involve a good amount of walking and little feet get tired! Even though we've long abandoned stroller use elsewhere, at the parks, we find they're essential. Of course, whether your little one is entirely comfortable is a matter of preference. Mine doesn't mind being a wee bit scrunched in his stroller. He's also average or a little under-average height and slim. He's just happy to be seated. We might all be a little jealous of that!
At that age, you might also find that a break during your park day is helpful, especially if you're hoping to stay later into the evening or visit over multiple days. We like to go back to our Disneyland Resort Hotel room to relax or take a dip in the pool on a warm day. It helps reset us and our little guys for more fun. If you decide to leave and come back, be sure to hang onto that stroller rental receipt. While it is possible for strollers to run out, you should be able to pick up a new one when you return to the parks by showing the Cast Member at the rental spot your receipt. Just don't take rental strollers off the property! They're for use at the Disneyland Resort only.
I hope this helps.
Elizabeth