willsjamie, I believe part of your answer is in one of your own statements.
"I've got an Earth Angel rose in a container that can't possibly be doing any better."
1)If it were my own root rose I would plant it in a container. I would carefully, gently transplant this rose Into a pot with "drainage holes" with a mixture of compost and organic potting soil. The potting soil should be organic. I would NOT use a potting soil that contains a granular fertilizer. It will void your guarantee and possibly kill the roots. After planting I would use diluted Alaskan Fish fertilizer once. Than follow up with plain water at regular intervals. I would fertilize using the Alaskan Fish every 3 to 4 weeks. Then site the containers into a sunny area.
2) Early tomorrow morning I would water the rose while still in the ground. The weather in your area tomorrow calls for Sunny, temps 66/48 degrees. In the later part of the afternoon I would follow the suggestions in the above first paragraph.
3) I would leave both roses in the containers till they have built up a sufficient root mass. At that point, I would plant them in the ground with mulch in a sunny area.
4)I don't know what type of soil you have in your garden. But it would be worth it to test the pH where you intend to plant your roses. I see from your photos that there are some bordering rock-like decor. If they are composed of cement it is possible they might have lime in them - (alkaline). I would test the pH in that area.
Lastly, I would use rainwater as opposed to tap water whenever possible.
Keep in mind, container planting requires more frequent watering.
5) As for the fluctuating temps, containers can be moved temporarily into a garage or sheltered area.
Please feel free to join the Rose forum.