-Replacing a sliding patio door with a French door.I will be working with contractors to get these done (not DIYing it). 

Keep every key tagged with a flexible plastic key tag that uses a clear plastic shield to protect the written label. 

Most long term parks require tenants to fully skirt their RV (so look for skirted units) and most tenants who really are staying long term will build an addition, deck or patio, install a storage shed, create a garden, and show other evidence that they have made this their permanent home.With that established, you can underwrite an RV park similar to a mobile home park if the above description of long term tenants is present at the park.

Along the way I also was able to get free insulation installed (~10k value) using the local utility energy efficiency initiatives as well as laid plastic sheeting in the bare crawl spaces to help with moisture and bring it up to code. 

Last month I started a major renovation which began with replacing on the sewer, then tying in the downspouts, replumbing the the bathrooms for a more optimal layout, running water and waste for a laundry in the upper unit, pouring a back patio, and remodeling the bathroom in the lower unit. 

I have done painting, floors, a backsplash, and a paver patio over the past year.

Replace w/ Drywall: $8,000Windows: $6,000 (optional...they are single paned windows)New Half Bath: $10,000 (optional...full ball + $5,000)New Appliances: $2,000New Front Porch Roof & Railing (optional, has existing patio): $3,000New Kitchen (optional...countertops, cabinets, fixtures): $10,000Purchase Price: $180kLivable ($1,100/rent) - repair floor w/ vinyl, fix roof, seal walls/ceiling, new appliances, new half bath: $22,750 + 20% overruns: $27,300 Nice: ($1,250/rent) "Livable" + new windows, new covered front porch, new full bath): $36,750 + 20% overruns: $44,100Excellent: ($1,400/rent) Gut house - new floors, walls, ceiling, appliances, kitchen, front porch, full bath, and new roof: $76,500 + 15% overruns: $88,000We'll probably target 'Nice' as I think that will give us the highest rent relative to costs.

I like to put a vapor barrier (layer of plastic) and reinforcement into the slab.

If not, I recommend plastic when you do -- they don't soak up smell like wood -- even painted wood.

There is a small patio area that's gated in with the unit, but hasn't been "enjoyed to the fullest extent" because of the smells.Can we hold them liable for breaking the lease?