Building a 30x20 ft platform and really need some advice

[Steve1101]

Hi there. First time trying to build a platform or deck and Building a 30 ft by 20 ft platform for a large canvas safari tent we would like it as close to the ground as possible. The tent covers the whole deck edge to edge and will be left up year round.  It's going to be on level flat l ground and  3- 4" crushed stone on top. It is being prepared by a professional ground working company.  I'm trying to make this inexpensive and very simple for me to put together.  For longevity I know this this is not smart but it's just from my family to use for camping down by the waterfront and will only be here for the next 10 years. I was wondering if I could use 4x6 ground contact posts as joists and just lay them directly on the ground 16" oc without having to do any blocking and just throw 5/4x6 decking on top and call it a day?
If this does not work and I brought this off the ground with 3 inch high blocks could I run 2x8 joists 16" oc  over a 4x6 drop beams to span 8 or even better 10ft between supports?  in that case would I have to just do blocking over each beam ? No blocking at all? Or would I have to block in the joist and the beams?
Thanks I appreciate any help I can get.