Have you posted photos of your pond? That might help with ideas. But we bought DIY aluminum fencing panels and posts to keep our dogs off the pond when it was frozen/snow covered. They are easy to install - you just push the posts into the ground - and you can expand to as many panels/posts as you need. We got them at one of the big box stores.
where I live, if a water feature is more than 24" deep, a 4' fence surrounding is code. This was part of my thinking with enclosing the whole thing. I figure if I was going to have to have a fence anyway, why not protect from mosquitoes as well? One of the best things I ever did, especially as I read stories about bears pulling down chicken coops and moose walking through ponds, monster snapping turtles and 6' snakes, and any other mischief an open pond is subject to. Sure takes a lot of concern away!
I would imagine you can get the 6' garden T irons with the burrs for attaching wire fencing. Easy to pound into the earth and the metal garden mesh is sturdy and not expensive. You can easily roll it back up and store for another purpose when you're through.
I was wondering after reading this why you only wanted a temporary solution? Do you have a plan for the finished pond? I know there are various schools of thought on this one, but when my kids were small we were less inclined to block access to areas of concern and more likely to teach them to function safely around the hazard. For instance - we didn't put baby gates on stairs; instead we taught them to go up and down in a safe manner from the time they started crawling.
With our grandchildren, we don't allow them around the pond alone and we have a safety doorknob that we keep on the back door so they can't get out there on their own. When we are all out there together, we teach them where they can and cannot step or walk and they have learned to enjoy the pond without damaging plants or ending up in the water!
I did a raccoon and toddler proof cover for my pond in addition to a yard fence. I bent metal electrical conduit to shape, domed about 12" over the center, and attached black (black fades from eyesight view) chicken fencing over the whole thing. (I don't have pictures at the moment.) It was weighty enough to stay in place, sturdy enough that a small person can "fall" on it without going through, and lightweight enough to move out of the way when I wanted to.