Are there any temporary fixes for rear shocks on motorcycles ?

I have an old dirtbike (Suzuki DR400 1982) I want to go for a ride in 2 days and cannot get replacement shocks until next week. The rear shocks ground out when I bounce on the seat, they are at maximum adjustment is there any temporary fix to stiffen them up a little ?

(I was considering wrapping some sort of rubber like an innertube in-between the coils)