RBTA and "new" tank? HELP!

I need some help as I am in a bit of a spot and unsure the best way to proceed.
I bought a 20lb rock with 3 gorgeous RBTAs that are baseball sized and two really pretty clowns for $100 on Saturday. He was tearing down his tank and he just wanted them gone.  I intended on putting this in my mature 46 gallon tank, but this rock is so huge, it will not fit into my tank unless I do a major overhaul, meaning, I am going to have to remove everything and put this rock in first in order to get it in there.  I hadn't anticipated that.
So I need some help.
Right now I have the nems and clowns in a 28 bowfront that I set up a little over a month ago.  It has looked great all along as it was set up with about 40lbs a of already cycled rock.  It is doing great and everything is at 0 but nitrates which are .5. It has a few crabs and snails, but that has been it for livestock.  I have been ghost feeding it and getting no spikes.  On Saturday I shuffled things around and put the anemone rock and clowns in it until I could figure out what to do. The nems have moved, but remained on "their" rock, and two of them have completed impending divisions, so there are 5. Parameters have remained the same and I am watching them closely, but I know this is asking for trouble.
The eventual goal is that most of the livestock and rock currently in the 46 gallon mature tank will go into my new big tank that still needs to be set up and cycled, and the nem will be in the 46.
So, here is my question.  Am I better off to leave the nems in this tank and be hyper vigilant about water quality and water changes, just like you would in QT, or, am I better off taking everything out of my existing tank, so they can be in a mature tank, but potentially setting off issues there? Should I just take out the clowns and put them in another tank to reduce bio-load as low as possible? 
What would you do?

 

I have considered this and it is probably the route I will go if the general consensus is that keeping them in the 28 for about 2 months is not going to work.
Keeping the nems healthy is the primary consideration, of course. But I hate to break the rock as is it a really nice big display piece, and solid enough that I think breaking it will be a challenge (And maybe endanger the nems) so I am interested in all possible solutions.

 

Ideally, I would like to leave the rock intact as it would be fabulous once I get my big tank set up.  Also, I would prefer not to do major re-arranging in my 46 at this time, so leaving them in the 28 is best for me, but is it okay for nems?  I have never had an RBTA and I always hear how critical a mature tank is.  I just don't want to risk losing them.  Any tips or tricks would be appreciated. /DesktopModules/ActiveForums/themes/_default/emoticons/smile.gif