This is a property I plan to keep for a long time so re-selling is not an option.Pros/cons to this strategy in reducing management expenses?   

Hi Mathew,HVAC filters is a sore subject with me, as our lease requires our tenants to change the filters, it's stated in our policies as well and they do get charged a fee if we come out to change the filter.

If you really think that I'm not using other sources to do research you are sorely mistaken.

Absolute eye sore for at least 2 years. 

What was an eye-sore is slowly turning into just another place to live in town; not a ghetto.  

Don't put something that is going to be a "sore point" if you decide to sell.

Now she says that there is mold and she had to go and purchase mold remediation stuff this weekend etc.. also there is gap in the side garage door we installed so pests are coming in, and AC guy took time to fix the problem which increased her PG&E bill $200 and there is a stump in the front yard which is a sore eye etc..My gut feeling is she doesn't have money to pay so she is using all these as excuse.

I never have owned a mobile home park.My moms friends have been doing it over 40 years.Whether a park works or not depends on how states and counties and cities view them.If it's a suburban area to urban area here in Georgia they are grandfathered in.The counties and cities give you all kinds of grief.They find ways of pushing the park owners to sell off for development.In doing this the county or city gets rid of the transient renters,they eye sore of the park,the high crime,and they increase their per acre tax assessment base.On 10 acres of commercial the government would much rather have a nice new commercial development there than trailers.A junkie trailer sitting on land has very low assessment value.If you were going to buy a park I would look at the value of selling it off for development down the road and making sure you control the whole thing and can get people out ( a few people of the lots own the land for example and make it tough for you to resale down the road.)

Neighbor's shed demolished by our tree, ripping up cement in a 1910 home to figure out why the cellar basement has been clogged since Truman was president, painting a fence because the neighborhood complained to the city that it was eye sore, replace a balcony rail on a half porch because a 100 year old tree used it to conveniently break its fall (at least that was the only damage it did).  

Damages, dirtiness, disorderly tenants, disrespect, etc.