I do not know anyone that thinks Dricore is worth the money in our area.To me it seems like it would cause a huge increase in the wicking of water into the sheetrock if there was a leak.Where would the moisture go if you seal off the 1/4 inch gap around the edge with vinyl?

Make sure you are well compensated price-wise for taking this problem off of their hands, including a reduction for the 2 month's rent you have to try and collect and the damages you've already seen + a huge % for what they still haven't wrecked! 

Is there any way to protect myself now if they damage the property before leaving?

You may find that you need to drop rents a bit in order to retain the tenants, in which case you will effectively be subsidizing their fuel costs (because the underlying cause of the rent decrease was a fuel cost increase). 

It will also save you money cause you get a commission on what you buy.

I have a one page cover sheet I add to each application with check boxes to show that they have the "deal breaker criteria", a section to score the "nice to have" criteria, and a section to briefly explain my acceptance or rejection.Our Criteria: Complete applicationVerifiable rental historySufficient income/resources to pay rent and liveCredit report showing prior addresses consistent with application We do not deny housing for race, color, religion, sex, national origin, handicap, sexual orientation, marital status, or familial status.We do deny housing to individuals:convicted of manufacturing or selling drugsconvicted of a crime the poses a threat to the property or neighborhood, including repeated disturbances, gambling, prostitution, violence, threats of violence, or rapewhere there is poor prior tenancy: evictions, violations, damage to rental property, poorly handled move outs, amounts are still owing to landlords or utilities.who misrepresent information on the rental application

You'll have to give notice to cure to get them to be sure they remedy the damage.

He of course came back to sabotage my roof my driving long nails into it creating a leak that damage drywall.

While rehabbing, I spent a little extra money fixing things that could potentially cause problems down the line.  

ALL of them, obviously they talk about this cause I get the same old crap from each every time.A couple years ago they started on this false story of me wasting $100,000 on a complete gut rehab basement up rebuild.