Turntable on suspended floor - shelf or braces?

My setup is on a suspended floor over a crawl space.

I'm about to finally buy a turntable (Rega RP6 or RP8) and am going to have to to address the bouncy floor. I set up an old Thorens just to try it out and there is a severe foot-fall issues (who knows how bad other vibration will be).

Looking for suggestions on whether I would be better off to put the new deck on a wall shelf, or if I were to reinforce the floor itself?

The floor is over a crawl space with a few feet between the joists and the dirt, so I could easily install 3 or 4 jack-type supports that would bond the floor to the ground.

Does anyone have experience doing this? Would I be better off with a supported floor, or a wall shelf?

Thanks - djm
I just traded an LP12 in for a RP10 and had severe FF issues with my floor.
I had two Lally columns in my basement supporting three joists to eliminate
the flex in the floor. I also had a brace between the wall and the top of my
cabinet to eliminate any rocking movement at the top of the cabinet. If I
didn't step softly I could still force a skip. With the same cabinet and all
bracing removed, I have yet to have the RP10 skip.
My suggestion is get the table and see how it reacts first. Then I would look
at a wall shelf before I would ever brace the floor again. Soil can expand
and that expansion could cause the jacks/supports to force the floor joists
up and possibly do drywall damage or damage to the floor joists. That was
one of my primary reasons for trading off the suspended table, I had
noticed movement in the structure of the house that concerned me, e.g. a
door a few feet away not closing. I love the RP10 but have to admit now
after a time that the LP12 had a better sound that I miss. But it is close
enough and eliminates the structural concerns of a larger investment.
That said the shelf makes much more sense in the long term picture. Or at
least that is my opinion.
Don't get Mike Holmes started on that one...
Really though, if FF is so bad it is most likely going to muck up your bass as well.
A decent carpenter should be able to take a lot of the bounce out of the floor without much effort. You could either "toenail" in extra boards to the joists to make the stronger with less flex and/or put cross members between the joists. Either way, you would need a nail gun, a bunch of wood glue and some inexpensive 2x6 or 2x8 boards anywhere from 4 feet to 12 feet long...
it depends on how technical you want to get. Your interior walls that you may want to hang your table could be supported by the bouncy floors you mentioned. An exterior wall would load down to the foaundation in most cases and be the best solution for wall mount. The simple way to take some bounce out of a floor is to add a row or rows of bridging perpendicular to and flush with the floor joists. You are looking to increase your "load bearing" of your floor system and a google search of that would guide you further down the path of obcession.
I put a Vibraplane isolation platform under my suspended table and it solved all of the problems you mention but also isolates the table so well that I hear all sorts of new detail and extension. The sound improved tremendously. Details can be found on my system page.
My effective inexpensive solution for a suspended turntable (B&O) was to place cryogenically treated tempered steel isolation springs (Machina Dynamica Cryo Baby Promethean Mini-isolators) between the maple board the turntable rests upon and the horizontal top furniture shelf beneath.
For further vibration control, a VibraBlock Damper rests on the horizontal top furniture shelf.
As mentioned by Peterayer above, the sound is upgraded to a surprisingly impressive degree with appropriate isolation.
My turntable is protected down to about 3 Hz which is incredible for the low cost of the setup. When Godzilla next stalks the earth my vinyl won't miss a beat.