Hi Brookster,
I have fished the Combermere Madawaska river / Lake Kamaniskeg area off and on since 1983. Was last there in 2004.
If you are on the river, close to Lake Kamaniskeg, your best bet is to head onto the big lake. The fishing consists mostly of SMB, but you can get the odd walleye and laker, but in the summer they are not abundantly easy to catch.
The basic idea is to find rocks in the main lake, out by the two islands (Gull and Parcher). Depending on the water levels which are controlled by Ontario Hydro, the rock shoals in front of the islands coming from the river are only a few feet below the surface and are usually marked with jugs. Lots of smallies and rock bass. Worms, minnows and crayfish are usually best.
At the other end of the bay, past the two islands where the Madawaska flows in from Bark lake, drifting worms and minnows right on bottom in 20 -30 ft of water can produce some big smallmouth. There is a shed with a Canadian Flag painted on the door, that we used as a marker point.
At the other end of the river, below Combermere, is Conroy's marsh. Good opportunities for Pike, LMB, Walleye, Smallmouth and numerous panfish.
If you can get your hand on a fishing map of the area (I bought it in Barry's Bay at the bait shop), it would be more than beneficial. It helped me find the area in front of the shed with the flag on it.
I probably sound like a know it all , but I always enjoyed the area, the fishing, the lake / river etc. There is over 90km of navigable water, just not sure how far you plan on travelling on a pontoon boat.
Hope this helps!
AC