In your situation I d be most worried about rodents and flat spots on tires. Looks like you got the rodents covered, just don t want them to rot for a month if you catch one. The smell will be hard to get out.
I wouldn t be concerned about the pitch in the ground.

 

I have used Tire Cradles for 15 years. I think they were about the same price I really don't remember. So I figure about $10 a year. Never a flat spot after all winter long storage.

 

I also slather leather conditioner liberally before it goes into storage. Figuring I won't be in there for a while so it can take its time getting absorbed.

I pump up my tires ~+10-15psi. Haven't used sta-bil as I fire it up every few weeks for about 30 minutes or so. I do the same with my winter car during the summer for many years now with no issues. They are on battery tenders during storage.