Justin Slife recommends you get bar safety straps from 10-0.
This is good deal. (You might spend $50 making them yourself.)
Bar Straps, 8 color coded pairs to denote different lengths. Must be used with PVC tube on T32SB Strap Bar. Used to train over grip, under grip and eagle grip giants. Requires wrist bands underneath bar straps.
Don’t be confused by the 10.0 text above. Certainly they can be used with or without PVC tube (shown on left photo). I prefer without, though both methods are useful. And they can be used on any horizontal bar.
Working eagle grip (el-grip) in straps is possible — but be very, very cautious.
Gymnastics Coaching.com 