Having the ability to raise and lower water level is a big plus. I do like the way you think and I would like to hear some input of other SMB guys on this. The farm I bought my first stock from places "tubs" of gravel into his ponds prior to the spawn and has had relatively good luck with that. I'm thinking of trying that method myself. I can't have much exposed rock during times outside of the spawn because of the high number of rattle snakes I have. If I have riprap much more than 2ft above waterline, they will move into it.