....Here is a concern I have about building structure now. I'm only 1/2 full. Could any structure I throw in affect the ability to later seal the pond if needed? I do not think I have a bad leak but I don't know. It has been going up a little each day.....
Since you are still concerned about leaks, you way want to consider initially placing more portable structure/habitat such as pallets, that can easily be removed if required. Some folks even attach pallets to shore by ropes so they can reposition or remove them. The archives show many examples of homemade and store bought structure that could be removed from the pond relatively easily if required.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=92463#Post92463