My old BOB Yak trailer mounts to the bike axle with stainless steel grenade pins, which works fine. After all these years, alas, the rubber straps securing the pins to the frame have rotted away. The original straps are nicely molded affairs:
I snipped a large O-ring, deployed four small cable ties, and this ought to last for another decade:
The strap in the first picture hadn’t quite broken, but the rubber was cracked and ready to snap. So I made a preemptive strike…
And, yes, one can buy replacement pins and straps, but where’s the fun in that?