Thanks for the info and ideas, folks!
BDJ, yes it's the Scadden Madison River. The standing platform and lean bar were removed for this trip to save weight since the portage to the lake was fairly long. It's a great, well-designed boat, and extremely durable. The anchor trolley system is awesome! I fixed my only major problem with it by putting stick-on grit tape on the standing platform---it was too slippery for my flippers.
Thanks for the battery info too, all -- my first run with the trolling motor was NOT successful, but after reading this thread, and checking the internet, I think my battery was at least 3 times larger and heavier than I needed! I was up at 100 amp hours, and it was too heavy. I have a #30 lb thrust troller, and duckster's battery says 33 amp-hour on it....that's more like it! How many hours do you generally get, duckster? Also, I'm familiar with the smaller batteries mentioned, Sportsmans Warehouse has them. I think I'll go with the 33a-h battery for when I use the troller, and the smaller one when I'm not.
Great ideas on transducer mounting, too!
Now the hard part, figuring out which sonar/gps will do the lake bottom mapping i need!
DANBOB