As long as the low temperature at night doesn't fall below freezing, you can leave them out. Beware though, any new growth and that anemic garage growth will be killed by a freeze so bring them back in during freezing temps.
If you have a garden wagon or two, place your potted roses on them for easier back and forth.
Or, get a small greenhouse. Your roses should be fine if placed in an unheated greenhouse. I'll be pulling my overwintered cuttings out of the coldframe in two weeks. The tiny repotted plants will be placed on shelves and will do fine.

Here is a link that might be useful: 10 x 12 greenhouse for $549.99

I prefer that the anemic garage growth does not survive, actually. Do you think they can stay out to about 29 degrees or should I stick to bringing them inside at 32?

Leaving them outside will take care of the sticky mess inside of the garage, but not the aphids. Do others have this aphid problem with potted roses?

Thanks.

Normally 29 is OK. I get aphids on my potted roses in my unheated greenhouse but soon thereafter the lady bugs arrive and take care of the problem.

When mine go out, I don't even think of bringing them back in unless the forecast is for temperatures below 28F. And that isn't because the 28F scares me, but because if the forecast is wrong, and it gets down to under 25F, I don't want to be running out there at midnight shifting large pots.