HI Mavro,
Mate run another bracing around the bottom, make it slightly larger than the other one, then use rubber buttons instead of padding, although jerry cans are tough, the constant jarring will split the jerry or it will rub through. Be also mindfull that a full jerry and an empty jerry behave differently when exposed to the climates, you will find the jerry will expand slightly in the sun, some may say to open it to releive the pressure but it gets rather messy as petrol will launch out of the can if done incorrectly.
AC