Re: Sand And Weighting ?s
Just a tip Kayper, throw some line breaks in your posts.
You can hit enter all you want while typing for them, it does not save the post doing that, and it sure makes it easier to read.
That said your concern is potential vibration...
In my experience it is only 4 things that make the most difference in what you feel.
The first of course is a solid mount and good drive train.
If your motor can vibrate with a poor mount or buck because of a misaligned chain or poor sprocket, you will feel it. Pay attention to this if you do ;-}
Second is road vibration which you with licked with front shocks.
Third is as mentioned a really good saddle with a seat post shock.
Last but far from least is the hand grips.
The stock hand grips are hard plastic junk that will make your hands ache no matter how good everything else is after an hour.
I just cut the one off the throttle and throw it away along with the matching one they include for the clutch side.
The throttle barrel that fits over the handlebars is obviously wider so few regular grips will fit over it, but those $8 foam BMX Racing grips will with a little dish soap, hot water, and some coaxing.
Check for the Handgrip topic here for more, but their nice foam padding will impact what you feel as much as most anything.
On the sand...
Unless your frame is like beer can gauge aluminum you shouldn't need to worry about it.
With your nice long seat with a shocks pipe will reinforce it pretty well on the business side, though I do like camshifter's expanding foam idea for the seat post if you are worried.
Even with front shocks I can't see anything in the handlebars doing anything but off-setting the center of gravity higher.
Comfortable grips will do more than anything else for your hands.