A molly might work, but the amount of projection will vary based on diameter. This would be easy enough to estimate with one in your hand. Even so, use the supplied machine screw to collapse the molly, then remove it and either cut it shorter or get a shorter machine screw at the hardware store. Those machine screws need to be long enough to engage the end at full extension.

Here is a link that might be useful:

Hello, The frame for a pocket door looks like a ladder. The rungs are about 1x3. Maybe a rung is in the right place to mount the towel bar to it.All you have to do is find one . Tap on the wall, or a bent wire slid to the inside with the door open or use small finishing nails to locate then patch the nail hole.
Good Luck Woodbutcher

The horizontal frame work for the pocket of a pocket door are placed at 16"OC. vertically.
Depending upon the age of the door frame they could be 1x3 or 1x4.
Find the frame, install your fixture.

Hercules Hooks (See image at link below) might work for you. They do not extend too far, yet will easily hold up the rack.

Here is a link that might be useful:

Then again, maybe these Hercules hooks won't work! They are designed to hold things like pictures. Your towel rack needs to be secured so an upward movement does not jar it off as well.

Sorry about that.

I’ve used Hercules hooks to hang pictures on a wall with a pocket door on the other side. They worked great. But you’re right - I don’t think I they’d work for a towel bar.

Welcome to Houzz and Gardenweb, Emily. I have to say, though, it seems a little odd that you apparently registered today so you could respond to a decade-old thread with what WON'T work.

The person who asked the question, "Imuscle," has never been back since.

Maybe you just didn't notice how old the thread is. For future reference, the original posting date is right at the top of the post, just below the post title.

Fortunately, Woodbutcher (who IS still active) answered the question the same day it was posted, with something that WOULD work. So let's hope that Imuscle has been using and enjoying his or her properly mounted towel rack for these 9-1/2 years. :)

Again, welcome to the forum! We're looking forward to your helpful posts on current topics.

Thanks for the tips, Emily. I too read old threads for answers to my own questions. Guess DavidR was having a bad day.

I'm trying to solve this problem today, in 2021, so all relevant for me.

Jessica, what did you go with? My pocket door frame doesn’t have the ladder that was described (for those who may doubt, the door isn’t installed yet and I can see they don’t exist) so that route is out for me. The Molly with a shorter screw might but husband is reluctant.

alwayscold-

Tell your husband to install molly bolts with the door in the closed position (meaning not in the pocket). Once the backsides of the molly bolts have been compressed, they will stay in position and will not be anywhere close to the surface of the sliding door. Then all he has to do is remove the bolts and take them to the hardware store so he can buy short ones -- probably 3/4" or so --with the same thread. The original longer bolts are only necessary for installation of the part that is inserted on the wall; the substitute shorter bolts will have exactly the same holding power. If he is still reluctant, I don't know what to say...I've done this a number of times with no damage to the pocket door. You can easily determine how much room you have to play with in picking a bolt length by figuring out the distance from the surface of the sheetrock to the distance of the installed door and using something that is 1/4" shorter as a margin of safety.

Alternatively, I've installed 1/2"-3/4" thick wood blocking on the backside of the sheetrock in a remodel situation. You install the pocket door frame, you install the sheetrock on the side where you want to hang the towel rack, and, before you hang the sheetrock for the other side, you insert the wood blocking and have one person hold it in place and another who screws through the sheetrock and into the wood to bring it tight against the backside of the sheetrock. Once you've done that, you can attach the towel brackets with short screws into the concealed wood blocking. Then you close up the other side of the wall.