Yep, they are probably there. I think the bite in the morning right now is better though. Primarily because the forage will be there early. Not to say you can't catch them there all day, but I'd only stick it out for an hour without a bite before trying something different. If the pads happen to be there next spring (assuming you can fish during the spawn) I'd definitely try it again. I think like anywhere on the lake, you have to try to pattern the pads. If you do get bit, try to find out as much as you can about the area. It's not uncommon for the fish to be at a specific depth in the pads. The bottom is also important. It may have a muck bottom in one area that won't hold fish, and as soon as you find a hard bottom, there the fish are. It might be that the fish hold where grass and pads grow together. Like said, if you do catch one, try to learn what was unique about that specific spot. If the frog won't get bit, try a jig, beaver, or creature bait, and flip it into voids. If it doesn't get bit on the fall (reaction strike), I'd jig it a couple times, then pitch to a different spot, with the goal being hit as many spots as you can until you've caught one. Look for anything different about the pads, and pitch to it. A hole, a break, a clump etc... I think it's also worth fishing the edge with a worm, crankbait, spinnerbait etc.... If you're going to fish below the pads, I'd spool up some 30, 50, or even 80# braid. The frog should catch just fine with it as well. No use even trying with a whimpy mono. At least not in the pads that I like to fish.
Take some pics next time out. I like seeing those pads on the water!