I think that the Zeus likely will not last long enough without some help. The 36 lb troller will draw pretty heavy and if you have to fight wind it will probably eat the battery pretty fast. The next size up probably will not be enough either unless you use two in parallel. The solar panel with the small car starter battery will work, but if you use it hard for more time you can get it pretty well discharged. I have gotten into the habit of holding position in heavy wind and fast water and it seems to work OK. I have had it discharge fairly far down, but it doesn't take long for the panel to bring it back. If you go the panel route there are a lot on ebay and prices are pretty low. Just be careful of the size.
