I share your concern, but it depends how long you plan to take to prepare for the GMAT and complete the applications. I can't recommend that you are not working the entire time it takes to prep for the GMAT and apply if that is more than a month to six weeks. The overwhelming majority of applicants prepare for the GMAT and complete the applications while working, many at very demanding jobs. You may appear less competitive if you take off for more than a few weeks, and you certainly will not be able to show professional advancement during that time.
However is it possible for you to take off for a short time while you prepare for the GMAT and then either return to your company or take a different job that will allow you to complete the application process? Alternatively, can you just take a different job that is somewhat less time-consuming.
Thank you for your input. If you are familiar with the book, The 4 Hour Work Week I was planning to take a "mini-retirement". For me, this entails moving to China for 6 mo-1 year to teach English, while living off of savings and using my copious spare time to prepare for the GMAT and to write application essays. I believe it would be valuable experience, but I'm not sure if the AdCom would think so.
kudos are appreciated