If I were you, I really wouldn't do that at all. First, jelly is not all that safe of a material at only a "2" on Eden's safety scale. Seriously, they have some very questionable chemicals.
Second, dildos and power tools don't necessarily mix. Not too long ago there was a woman who took a rather embarrassing helicopter flight to the hospital after getting injured with, yes, a dildo attached to a power tool.
If I were you, (and of course I'm not and the choice is ultimately between you and your girl) and were looking for something with some oomph, I'd check out a Hitachi with a head attachment. My two cents.