Even if it is permissible, fight them at your own peril. 

you have my permission to raise the rent.. :)

If he has a lease and has allowed 'friends' to move in, then they have received permission and thus did not trespass. 

I'm selling my home as a for sale by owner. Four months ago, I signed a standard PTS agreement (Arkansas) with an agent, who was temporarily helping out a Buyer (who did not have an agreement with any Listing Firm). I...

That said, you could reach out to the seller and ask for permission.

The tenants did give her notice and permission to give me rental history.

I won't ask them for permission to land mate "DingoAir" lands whenever and wherever the F*** it wants hahahaha

Things like "it's out of underwriting" and "the appraisal has been ordered," but NOT thing like "we're waiting on this specific condition" or "this is the buyer's FICO score" without permission.

I would also add to your contract that the seller is giving you permission to do that.  

You don't need permission because you have given them notice of intent to enter.