I think I found a good way to utilize 1.5" needles to shoot quads, delts, and other low-fat muscles.
While I've been waiting for 1" needles to arrive, I rigged a needle cover to help me use the 1.5" needles I had to shoot quads and delts.
I cut an the tip off an extra needle cover so that when placed back over a fresh needle, only 1" is exposed, making it easier to fully press the pin in. The plastic guard acts as abrace, like a second hand would, which allows you to self-aspirate a delt shot without the needle moving.
Obviously, the short-guard would be wiped down with alcohol before each use.
See photos below.