So I did set ulimit and it didn't work at all.
Why? It seemed like dsmetool modified the ulimits, so a google search was in order to find the dsmetool source if possible. Well, I found it soon enough (http://www.freemoe.org/users/jebba/s...til/dsmetool.c) and what dsmetool does is to signal dsme, again closed source, through dbus to load the process, so the process will inherit dsme ulimits and not the rc.d script's.
The workaround, to try next, could be little ash script daemon to poll every few minutes the gpsdriver vmData size and kill it when it grows more than a given size.