@Moondog now I understand so much better why you want to move your roses.! Your project of redoing the beds is excellent although a lot of hard work...good for you!.
I would pick up Seil's
@SeilMI suggestion and just lift your roses into buckets or some type of container. I use large pastic bags for the same purpose and keep them in an half shade position with an eye on their watering needs. Perhaps every other day in the summer or even every day if it's too hot. Once the soil improvement is done you can place them back. This can be done all season along. It only requires diligent observation of your potted bushes. So you can consider redoing your beds by parts....yes of course one discovers things not exactly in the best time of the year...
but really roses are very tough ladies...imo they seem to "understand" that's for their benefit and contribute to one's effort by growing the best they can meanwhile...
Arturo
PS. Gravel under is not necessarily a bad thing for your roses specially if your soil is hard clay. How deep is the gravel layer?. If it is between a foot or 18" deep then I wouldn't bother to remove it. It really helps for drainage. What you seem to be indicating that your soil needs ammending to improve nutrient content, aereation, and also better drainage in the upper layers. Is that so? Learning about your soil's natural properties is a life-long learning process. After gardening 35 years here I'm still trying to understand it...