Yeah, as mentioned, heat and time for taters. If you've had smoked potatoes, there's just no substitute. If you try to smoke them @ 225*, unless they're small yellows or reds, they'll take an eternity, barring cutting them up in a pan. I have actually put my potatoes into the smoke before my meat on occassion, just so they'd be done about the same time as the meat. The only time I've ever covered my potatoes with foil is when cut in a pan, after a couple hours of smoke...I've never wrapped in foil, though...defeats the purpose, IMHO.
I have smoked large Idaho Bakers in the past, and will continue doing so. A 1-1/4+lb Idaho will take all day @ 225*, and then some. 240* will shorten cooking time significantly. 250-260* and they'll scream right through to a tender state in about 1/2-2/3 the time it takes @ 225*...must be due to reaching boiling-point internally that much faster, and staying hot enough to create enough internal steam for a longer time.
When you squeeze the potato to check cooking progress, they'll feel hollow when done...that's the flesh shrinking and pulling away from the skin. When you bring them out, if not quite finished, just put them straight into in a covered dish to rest, and they will continue cooking for a bit before they start to cool down.
Lastly, there's no shame in using the nuke-box to finish them....been there...use the tools you have available to bring the meal to the table. I'm like many who like to do the cooking on the grill or in the smoker...start to finish...that doesn't always work out.
BTW, if you're smoking on a horizontal w/SFB, the grate temp variations will be far more than you'd think. Also, the warming racks (if you're using it) may be much hotter or cooler than the main grate, depending on your internal configuration, vent stack, tuning plates, baffles, etc.