As I understand it, your lot rent can go as high as half of what a 2-bedroom apartment rents for (and that a 3/2 POH in good shape could go to 100% of the cost of a 2 bedroom apartment.) But I have been looking in two Texas cities (Denison and Abilene) and the lot rents at the MHPs in those areas are way, way below that.
In Denison for example, an average 2 bedroom rents for $750 but lot rents in the area are at $250. Furthermore there is considerable vacancy in many of the parks. I did look at houses for sale in the area and in both places older 2/1 houses can be bought for under 50k. I am assuming that in some markets, you must not only make sure the median home price is over $100,000 but that the lowest priced homes are not less than around $75,000.
Each market is a little different based on factors like sf home price, quality of apartments etc. Percentages range from 20% in Lafayette, LA to over 75% in senior markets in FL. Many TX markets function in the 40% range, but a lot of times that is just due to Mom & Pops not pushing rents and that is latent equity. If the median SF price is too low you will likely have issues. Go to the Texas A&M real estate center website. Housing Activity - Real Estate Center They have tons of useful data, especially for communities in TX. Look not only at the median price of a home, but trends and also months of inventory. If a market is less than 6 months of inventory, that generally means there is a shortage of homes, and is a good sign.