did you ever get the chance to see the TV show "Crappie University" ?? I forget the guys name ... but he was always using Charlie Brewer Sliders, and either trolling them in creeks, or jigging them in treetops & brush. I never found out if he rigged them "weedless" when using them to troll, but he did catch Crappie using them (of course any "hang-ups would have been edited out ....LOL!!).
The only negative I can see, in using weedless jigs while trolling, is having to be able to set the hook "immediately" after the hit. Trolling is not "real different" from casting, as it relates to weedless rigged jigs ... you would still have to "see" the hit - determine if it was a hit or just the jig hitting an object - and set the hook ASAP, before the fish could reject the offering. But, trolling with multiple poles and weedless jigs could get a little tedious ... especially if the Crappie were just nipping the baits.
I find the actual "slider grub" to be a good bait ... looks a lot like a "minnow" (long thin profile) and has good tail action. The "slider jighead" does seem to lift the bait up, in the water column, more so than other jighead shapes ... generally requiring a heavier slider jighead, in order to stay at the depth you get from the other shaped jigheads (of lesser weight). The hook is larger, per related weight of the head, than most other jigheads ... and that may require a little stronger hookset and/or heavier line.
You could rig the slider grub on the slider head - non-weedless ... or you could try "Texposing" (skin hooking).
These are just my observations and opinions, as I don't troll enough to really have any vast knowledge base to draw from ..............luck2ya ........cp