Would appreciate some thoughts on solutions to a problem.

I have a large concrete parking area in back of the house. I use it as a
workspace for a number of different projects. A variety of machines are
parked there at various times.

The pad is exposed to direct sun, with no shade. This makes project work
during much of the day rather brutal.

I'm looking for some form of portable shelter that I can easily move around
to cover the project being worked.

I've tried the approx 10'x10' portable shelters. They're fine, except they
have to be guyed to stand up in any wind. Moving them to get a boat or
tractor in or out is problematical because of the need to move the guys
also.

Right now I'm trying to use a patio umbrella. It's a 9' canopy on a 8'
pole.

My problem is trying to find a base that will keep it upright so it won't
tip over in light wind. I've tried the cast iron ones like Lowes and Home
Depot sell, and they simply aren't enough (they're approx 50lbs or so).

So, would appreciate thoughts and ideas of inexpensive, readily obtainable
items that might make a good base for my patio umbrella. One thought is a
barrel of sand. That's heavy, but I'm not sure I can get around the
ultimate base being heavy. Heavy is acceptable.