Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: IB+ Gold, TK E+, Hyatt Globalist, Marriott LTP, IHG Diamond
Posts: 14,182
Are you trying to go from J to F, or Y to J?
First, my sympathies if you are going RTW at the back of the bus. Secondly, a single leg Y to J upgrade is going to be rather expensive and, as mentioned, any promotional check-in price is probably not going to earn you any additional TPs.
Have you exhausted all 16 permitted flights? Perhaps you can squeeze in some indirect routes for added TPs.