I use screen-door spring(s) at each end of my wire antennas to permit
tree/limb movement without stretching the antennas. You should be
able to buy such springs in several strengths at 'most any hardware
store (probably even WalMart or K-Mart) in the USA. If I think one
spring might not be strong enough for a particularly-heavy antenna,
I just parallel two springs.

Of course, the springs are between the antenna insulators and the
ropes used to pull/tighten the antennas.

If you do use weighted buckets, be sure to tie ANOTHER rope to the
bucket and a nearby limb so the bucket won't fall on someone's head
if the antenna rope or wire breaks!

--W0PBV.