Whats the worst that can happen on this deal? No tax records

I am ready to put my first deal under contract, but the seller does not want to show me his tax returns. I assume because he cheated on his taxes.

He will carry paper and the numbers look good and he will carry a note on the property with 25% down.

What is the worst thing that can happen on this deal as I do not know his true numbers and some of the rent is paid cash so his bank accounts wont match.

40 space park

35 lots rented according to seller, handyman and manager. I believe this is true from my looking at the houses.

5 park owned homes on the empty lots.

Average lot rent this park $155. Some as low as $125 up to $175.

The nearby parks are $145 - $175 with one park at $220. All the other parks in the area look 95-99% full.

Tenants pay electric and gas direct, water is submetered to all tenants.

25 park owned homes with 20 of them rented at $300-$400 a month. I plan to sell to existing tenants over 2-4 period at their current rent and convert everyone to lot rent only set at $199 a month. The other lots I will slowly build to market rate.

5 vacant park owned homes - 2 are supposedly going to be filled this week. I looked into 4 and they all need work but appear salvageable.

I am running an ad in the paper this week, but I think there will be calls because it is in a large metro area over 500,000 population and relatively low unemployment.

If I assume only lot rent and a 70% expense ratio the NOI is $45K. Sales price is $375K. 25% down and a balloon in 10 years.

This is roughly a 12 cap for what seems like a decent park with an upside.

The only negatives are the homes are pretty old and ugly and there are lots of potholes in the road to fix. The very back of the park the road is ruined, but I can just fence that part off as no on needs to drive on it anyway.

This seems safe if I do all the due diligence in the home study course. Any reason to back away from the deal?