Contrived to non-contrived tenancy..is it possible?

I think you need to separately consider contrivance and commerciality, and can you show that any contrived tenancy has been replaced by a new non-contrived agreement taking effect from a later date. I found the comments in this thread helpful when looking at this:
https://www.rightsnet.org.uk/forums/viewthread/7040

There is no equivalent in the CSPSSA to S17(2) of the 1998 Social Security Act ( which is the enabling provision in the Social Security realm for making Regulations to provide for certain determinations to be conclusive for further decisions).  This means that all previous determinations made by a decision maker or for that matter by a tribunal can be re-visited when a decision is made on a new claim.

In AM -v-Chelmsford Borough Council (HB) [2013] UKUT 245 (AAC) Judge Wright held at [48]

The decision of Mr Commissioner Turnbull (as he then was) in CIS/2540/2012 is to similar effect, though he was concerned with two notional capital decisions separated by a period of time.He decided that section 17(2) of the Social Security Act 1998 allowed to be relitigated on the second appeal whether the claimant had deprived herself of capital (per regulation 51(1) of the Income Support (General) Regulations 1987), notwithstanding that the first tribunal had examined the exact same issue . The said section 17(2) precluded an issue estoppel arising.

Judge Wright’s reference to CIS/2540/2012 is an error in drafting.  The correct reference is CIS/2540/2004.

In short, the new decision maker can and should look at the evidence afresh as must the Tribunal if the case goes to appeal because the new claim is refused