Or is there an acceptable or usual profit sharing for this kind of arrangement? 

Tell the tenant what their options are and they can either accept it or you can go in without them.

I was willing to accept the fact that the land trust has a title insurance policy in place in lieu of a lender's title policy.

If so you could qualify for the 121 exclusion and take the first $250,000 and $500,000 (If Married) of profit tax free, and put it into your next investment property.

And the time it was your primary residence (tax free up to the $500K exclusion).   

Seller accepted the last, it's pending now as-is. 

I listed my 3/1 house with her and the first hour, with the first offer, I accepted to sell my house clearing $10K more than I was going ask for without a Broker.

For  your situation the safest is probably to just say credit score for both must be acceptable, if that is a criteria. 

However, in this case it’s worth circling back in 3 months, 6 months, or a year because this seller wants to sell, he’s just not ready to give up his fantasy deal.If the seller’s response is acceptance of the outline of my offer but countering on price or terms, it may be worth negotiating because we MAY be able to get to YES.My biggest profits have occurred when I made offers that were nowhere near what the seller was asking and yet WERE ACCEPTED, or with small modifications. 

However, it adds complexity with more paperwork and potential self-employment taxes on all the income.Doing it as an individual is simpler, with everything going on your personal tax return, and you might benefit from the home sale exclusion if you end up living in the property for a few years.