I once had a Garmin GPSMAP 76 8 MB memory which was similar to the Etrex Legend.  The 8MB memory is tight, but I recall most or all of Quetico topos fits in that space.  You'll need the Mapsource Topo Canada v2 (~$100) & then you can load up the topos you need + campsites + portages.

FYI:
1) Loading too many campsites (waypoints) makes for a very cluttered screen, so don't load the whole database (might not fit anyway)
2) If you load portages as tracks, you can only load 10 of them.  If you just load portage ends as waypoints, the limit is much higher.

There is much more about this somewhere in the Inukshuk forum.

Good luck.

-Tom