There's a graphite version of the battery bar. I don't know the part number. Because it's graphite you have to be careful depending on the type of battery that your battery wires to don't touch. I have not run a shorty pack, But it might work well if you move it to the rear of the battery tray. I guess that would be a case where you need less weight, less steering and more rear grip. Try it and see what happens.
The graphite strap (9851) is actually designed to use with the same 9879 Thumb Knobs as is currently on the OP's 10.3, so won't really alleviate his dissatisfaction much ... a couple options may be to use the 1787 Thumb Screws used on the B4's, where they can just be 'spun' on, making it a bit easier ... or a couple 4/40 Socket Head Cap Screws WITH HOLES, and use a body clip to hold the strap down ... or, you could even cut a couple slots in the sides of the battery tray, and use the 71050 velcro straps like used on the ProSC10, DR10 and T-Rat ...
https://www.associatedelectrics.com/...h/?query=91458
https://www.associatedelectrics.com/...h/?query=71050
https://www.associatedelectrics.com/...ch/?query=6929