All the better brand pullers of the period, like Snap-on, K R Wilson, and Plomb came with a screw-on cap for the axle threads to protect them better than the reversed nut can. This is usually lost over the decades, but you can make one by cutting down a cheap modern "knocker" type puller (only about 5 bucks) and drilling in a snall depression to center the puller ram.
On the 3-leggers...I once had to pull a VERY stuck Model A drum with one. It nicely illustrated the problem with this tool on a 5 1/2" circle...the drum SPLIT across the friction surface from the distortion of the pull. I assume the hub was permanently distorted, but didn't check...all of that was rusted junk enclosing a nice gear set.
The sound when that thing split must have sent every dog in the neighborhood three feet into the air...same for the later BANG when the hub finally let go.
Three-leggers were used, but as HUB pullers, not as pullers from the studs. Multiple tool companies sold Ford adapters for standard 3 leg pullers...these were lozenge shaped forgings with two lug studs OR bolt holes. The adaptor slipped into the hub slot on the Ford, and the puller attached to it with 2 legs. Pulled from the center like KRW, just a more awkward tool to assemble.