I have looked for bigger boots too without much success. I think it will come down to trial and error. After I did my lift I noticed rubbing on the boots that wasn't there before. I fixed this before it became an issue by loosening the clamps and re-positioning the boot a little so the 'folds' were not always in rotating contact.
Our cv's can easily handle the increased angle from a lift, but the boots struggle. CV's fail 90% of the time when the boot tears, grease gets out and bad crap gets in ( the other 10% is from severe loading, usually in offroad circumstances). The actual cv design is very strong at all angles of operation however they need constant clean lubrication. A good boot is essential.