I'd use wire screening such as this;
YARDGARD 308312B 48 Inch by 100 Foot Galvanized Welded Wire Fence
https://www.amazon.com/dp/B000RZAP4E/
Or plastic fencing;
Houseables Snow Fence, Temporary Fencing, Safety Netting, Single, Green, 4 x 100' Feet, Above Ground, Mesh, Garden Plastic Barrier, For Deer, Kids, Swimming Pool, Silt, Lawn, Rabbits, Poultry, Dogs
https://www.amazon.com/dp/B01N4AMZ8Y/
At first I thought you wanted frost protection, but the hazards you mention are never going away, so you'll need something that can be left in place and still allows good access.
The plastic fencing might be the best option.
I'd sink a steel T-post at each corner of the beds. Use a post long enough to accommodate a 4' tall side panel sitting on top of the raised bed sides.
Attach two 1"x1"s, or #4 rebar or something similar diagonally to opposite post tops, criss-crossing at the center. This will give the whole thing rigidity, and also allows you to put something cheap and lightweight over the top like chicken wire or bird netting.
Then attach the fencing. Use two pieces of (approximately 8-foot) fencing to wrap the bed from opposite corners, attached securely with zip ties or wire. The two loose ends are your "gates", so attach them with with hooks or something easily detachable so the panels can be pulled back for access.
