Can you sew or know somebody who can? Sand bags are your friend. Cut off jean legs or 8"x 16"(the size isn't important) bags made of cheap cotton that you can either fill with cheap sand from Home Depot(about $6Cdn for 66 lbs) or other garden shop. Or use cat litter without making a bag. Cheap too, but heavy to lug around. Either way, you can use cat litter to fill sand bags. Regular sand is better though.
Depending on your range, you can fill the bags on-site and dump when you leave.
The important part is that sand bags are more solid than anything and can be adjusted to fit your forestock by just bashing them a bit. As daft as it sounds, a sand bag is far more versatile than anything.
