my Rainbow was pre-liner days (it is from a pre-production run so before all the mods...) but I have had a play with the liner inside both the Rainbow and the DR .
Works for me at 172cm but of course it is a different story at 198cm (6'6")..
The Rainbow is a large solo but the DR is proportionally not as large as a double, so again it depends a lot on your size .
I don't think that anyone has ever done the full OT without rain (we had sleet in mid February...) so I did pack up the Rainbow wet at least a couple of times then and many times since , not a problem for me because I have a Chux (Handy Wipes) at the ready , set up the shelter and give it a quick wipe down inside.
As for the freestanding set up, I had mine done that particular day but did not bother with that afterwards. The DR does need some extenders to be able to do it, I made a pair about 20cm long.
If you like to spend a bit of time in the tent , not just sleep inside it, I would suggest the SS2.
I have a few videos with both the DR and the SS2 in my YouTube channel (francodarioli)
On platforms I am pretty sure my way of setting the SS2 up would be easier.
So start with one end clipped on to the hooks screwed in the platform side, then do the other end (don't pull the fabric taut) then insert the poles.
Just have a careful look at how I do it .
BTW, I don't sell them but look after TT in Australia, for example I do seam sealing if needed ($25)