i don't use 1mil tape so I don't know how well this will work. Will there be any problem with stretch if 1 mil tape is use at 30 ips ? I doubt many professionals, the prime users of 30ips, would use 1 mil tape for their work.
30 ips has no real physical demands on the tape beyond other speeds. With LPR 35, the coating is the same thickness as the 1.5 mil version, but the backing is 1 mil instead. Because of the thinner backing, print through
can be more of an issue, but I've never found that in actual listening the print through is any worse than with 1.5 mil tape. With either tape, storing it in the tails-out state minimizes print through.
Professional studios doing popular music don't necessarily rely on 'long' playing time. Most of the time, 16 minutes is enough to record several takes of a song. The famous Sun Studios used 7" reels for this reason. Professionals recording longer works will likely be using machines which can accommodate 14" reels. In all my years as a recording engineer, I used many 30ips machines which used 10 1/2" reels and never felt there was any problem. Besides, have you ever lifted a 14" reel of 2" tape?
1 mil tape is a popular archive medium.