Do you know anyone who runs a tow truck?
Have them stop by and take a look at what you have, they'll have some good suggestions for you.
I also use short straps around the axles then chains and ratchet straps both.
Use a short chain to pull the front axle back, then straps to pull the rear axle forward, and a chain over the trailer hitch to hold the rear down.
I'm not completely happy with that setup, but it seems to work fine.
In the future I'll have eyes in the front bumper for shackles and brackets bolted on with the front spring U-bolts for shackles there too. Then something similar for the rear axle and rear of the frame.
Some folks say to tie the axles down, and let the body float on the truck suspension. Some folks say tie the frame down enough to squish the suspension some, leave the axles alone.
I think it is best to tie down primarily the axles, and then the frame is a good idea too.
Hard to say exactly how to do it without being there to look and evaluate the situation.
But I don't think you can go wrong with 8 straps or chains total, 4 per axle with 2 forward and 2 back, keep them short if possible then they help hold it down as well as keep from moving around.
Grigg