Stitching a leather cover on a 69 rallye steering wheel.

I wonder if there was some sort of hard foam or rubber and method to install it to increase rim thickness of the Rallye Wheel.

The narrow-ness of the OE rim is uncomfortable.
I wrapped a pc. of heater hose around mine, but the old auto parts leather covers did`nt quite cover all around. You have to slit hose lengthwise, find the proper cover and it would hide it.