Caroline, that would be hard to determine w/o having a window that size, as well as the material of the shade/blind. I have the bamboo Roman's and they roll/stack to the bottom of the attached valance, covering about 12" of the upper window.

My largest is 43" wide and almost 60" long, and it's fairly heavy. I very rarely raise/lower, as you are needing to do, but I would be concerned about the cords breaking if there's too much weight, because of all the 'action' the blind will be getting. That would be my only worry.

In addition to the type of fabric you're choosing, factor in if/what type of lining there will be. (Because the fabric that you see looking at it from the room may not be what you want your windows looking like from the street -- say, if it's a dark-colored fabric, you might be persnickety like I am and want a white/natural backside, and a fade-resistant one at that.)

And, ditto to Patty Cakes' comment on the width and the stress of that on the mechanics.

I just bought a 76" wide cell blind for my kitchen window and even though the handyman seems to have installed it fine, I now wish I'd chosen the option for 2 separate headrails instead of one -- that is, 2 shades side-by-side -- to not have all that shade relying on one headrail and a handful of screws.

But maybe you have one large plate-glass window instead of 2 separate side-by-side windows.

My east window is made up of three side-by-side windows; two are 23" wide, the center is 50" wide. It would take three seperate inside-mount blinds.

Yes, I can be persnickety, too. I would want off-white, fade resistant fabric on the street side, plus blackout lining, and then a firm cotton fabric face. I would want the Romans that have the wooden slat at each pleat. And how do you wash these blinds?

They would have to stand up to being completely raised and lowered daily.

I'm going to assume you're going custom because you won't find these sizes in readymade. Fabric romans will project very little. Each fold pretty much just lies on top of the other. I wouldn't worry about cord breakage. When you go custom, the fabricator will know how to make them and what system to use.
You don't need a separate fabric for the outside. One side of the blackout looks like lining and is available in an off white.
You don't wash them, you vacuum them.
If you've never gotten custom before, be prepared for sticker shock. They will be very pricey.

I have Roman shades on windows that are almost the same size as your small windows. I think my window is 26x59.The shades flat fold and inside mount, no wooden slat at the pleats. They have a white lining behind the gold fabric. As you can see in the picture below. The shade stacks neatly behind the attached valance and does not project out past the window trim. I guess though it would depend on how much depth you have on the inside mount area. My previous shades were a hobbled style and they did project a little bit.