ball joint idea's

ok so im having an issue installing the spindles back onto my car. the ball joint just spins when i try to tighten the nut down. ive tried to put a jack under it to tighten it down. issue is i dont have any weight on my car right now since the motor and trans are both in front of it. was thinking about stacking sand bags on my K member but that will kinda suck to do. since its high enough up in the air that its hard to get to. and low enough that getting them on the K memeber from the bottom will also not be that easy
another idea i was told was a tie down strap around the control arm attached to the coil over sping on each side. and compress the spring to push the ball joint in so i can tighten the nut down.

anyone else have an idea short of buying some $500 snap on ball joint tool

if i could get an impact on it i would for sure but there is no room for that. im going to try a few things this weekend