Again I wish you the best:
How ever I must say my extractor itself is balanced, with out frames in it does not move.
However With full frames it does shake pretty much, yes it will hold 7 gal. of honey with out getting in the lower bearing, and with two 5 gal. buckets of water on the lower built in stand it does move some.
The motor driven extractors I have seen have holes in the legs to bolt them to the floor. { I'm working on that }
My RPM is from 0 too about 350-400 RPM. I start at 0 and slowly work it up to about 100 rpm about 20-30 sec., wait about 10 seconds then ease up to ward the top end, by that time they are empty.
I've never tried extracting refrigerated honey, I like about 90 degrees or so, that way the honey is thin and extracts just about completely.
I can run 10 mediums, 5 fulls or 5&5
Again good luck, nothing wrong with trying a idea.
Oh, and I am in NO way trying to diswade you in anyway, us do-it-ourselfers are a minority, and have to stick together.
Bee-Bop