All Packed, but a bit puffy...

That's why you wear both pairs of shoes at once.
Have a good trip.

I typically carry my RS rolling carryon, too. You won’t have an issue. DH carries an Eagle Creek carryon that is actually a bit larger and he’s never had issues stowing it.

Can you fit the 311 bag in your personal item until you are on the plane?

Wear your heaviest shoes. Put your lightest shoes in the bottom of your rolling carry-on (wheel end); I use the same suitcase as yours. Put your 311 bag in your personal item (your tote or backpack) along with any drugs and supplements you need. Hopefully you're only taking two pairs of shoes. I took three last year, but it was a waste of space and weight.

After a couple trips fussing and stressing about how deep I can make the bag, I can now get it to 9 1/2 inches and 20 lbs. United didn't care. I wore my extra small crossbody purse and they didn't say anything. If United had, I had room in my tote for it. Tote weighs in at 5 to 6 lbs and squishes under the seat. Lots of people had carryon bags larger than mine, but I didn't want to chance gate checking. Just try to make everything as small and tight as you can and you will be OK.

Have a great trip! Post a trip report with packing report when you return home.

PS Don't overpack the carry-on's front pockets. Easy to do but no way to squish them down.

Wear your heaviest shoes.

I wear my lightest shoes. I also wear my heaviest shoes.

No, I don't have 4 feet. I only take one pair of shoes, so they are both my heaviest and my lightest!

Packing light means only taking what you know you will need. I have one pair of feet, I only need one pair of shoes. End of story.

But, but, but, but.

I have one pair of feet, I only need one pair of shoes. End of story.

Those 3-1-1 bags are terrible. The items themselves can fit nicely somewhere in the bag, but never in a conveniently accessible location! This issue also increases my own bag thickness.

But with a softside bag (great bag, BTW - I love mine!), you should be able to "squish" into a sizer if needed. Try to place the 3-1-1 near a less-stuffed end of your bag. For me, that's usually near the top area of the zipper, especially after internal items have settled toward the bottom. My 3-1-1 is not overfull, so sometimes I can also wedge it in next to my laptop or rainjacket in the electronics area of my backpack when I don't have my rolling bag.

And if you're truly worried, after going through security, unpack the 3-1-1 and redistribute the items into the gaps. Hopefully you don't have to do additional security checks during layovers.