You may not be aware of this but you DO have an Excellent bargaining chip.
When an investor is doing a short sale on his rental property, it does NOT help his "hardship case" with the bank one bit. The bank doesn't want to see that the owner is continuing to collect full market rate rent, but pocketing the money rather than paying his mortgage payment (if in fact he's short selling & hasn't been making payments too, which is likely) Other than letting you out of the lease completely, you should DEMAND to be able to pay 1/2 of your regular rental payment in exchange for Your dealing with people showing the property.
As a Renter, you DO have rights. If he doesn't let you out of the lease like you've requested, then you CAN refuse showings. Basically buyers would have to Write their offers "Subject To Inspection" at which time, once the owner Accepts an offer, that person does have the right to get into to see the property & you do have to allow access for them to see it. (the owner may accept more than one offer & put others in back up position, so you may still have to allow access for more than 1 buyer, however this method, I can't imagine you'd be showing the house to a great many people)
1. Owner lets you out of lease & you move
2. Owner doesn't let you out of lease & you refuse showings to only those whom the owner accepts an offer from
3. You stay & pay 1/2 of what you're now paying & will allow showings to anyone at reasonable times of the day with 2hrs notice. Also get in writing from the owner to get your security deposit back (he may have spent your security deposit)
I am not an attorney, but this is how I work with tenants when I'm doing a short sale for an investor.