Multiply 1.07 times the new amount.  

So for that I would use AirDNA data to figure out the average length of stay and occupancy rate for the market, use those numbers to get a rough estimate of how many stays per year, multiply that by the typical cleaning fee for your market, and then you have a yearly fee number to add to your total revenue from AirBnB so it is comparable to AirDNA's number.

Gross Rent Multiplier ? 

For an $800k house you may need to multiply that monthly property tax number by 5.

So you would take 88% (the LTC number you were using) and multiply it by the $160k. 0.88 x 160,000 = $140,800.

This is a general rule to start at, and used for average priced homes.You take the ARV of the house and multiply it by 70%.

You're doing this the traditional way and for things like an investment loan on a property, they will charge more interest on youDSCR- this is typically used for commercial due to the NOI and that's because when the bank will underwrite the property it's more focused on how much money the property will make and typically they'd go for at least a 1.25 multiplier AT LEAST or more due to the current market conditions

County tax appraisal information is an acceptable way to find out the ratio of the land value to the improvement (building) value, and then you can multiply the original purchase price by that ratio to get a reasonable estimate of the land and improvement values. 

Let them multiply your efforts, rather than you trying to compete with them.

Return On Investment or ROI in real estate is calculated very simply: ($ X 12) / Total Investment, where $ is the monthly rent multiplied by 12 months and all divided by the total amount spent on the investment.