Start by thoroughly evaluating leads for profitability, calculating ARV (After Repair Value) based on comparable properties sold in the area within the past six months.

All the BP calculators I've seen are based on LTRs. 

Or explore what BP has for calculators under the 'Tools' section.  

Upon sale, gains are taxed as long-term capital gains, calculated as the sale proceeds minus your adjusted basis (initial investment reduced by any return of capital).

Floor Plan CreatorPlatform: AndroidFeatures:Allows you to create detailed 2D and 3D floor plans.Supports laser measurer input for accurate measurements.You can enter exterior walls, fix them in place, and add rooms within.Offers automatic calculations for perimeters, rooms, and walls.Bonus: Plans can be exported to various formats for further editing on Windows2.

Further, how do I calculate the business use percentage for a rental RV?

For tax purposes, the profit is calculated as the sale price minus the cost basis (purchase price + renovations + transaction costs).

Consider cleaning, lawn care, snow removal and supplies as well as utilities  in your calculations.  

,Buying, renovating, and selling is a great strategy, but here are a few things to consider:Start with the Numbers: Make sure you know your ARV (After Repair Value) and work backward to calculate your budget, including purchase, renovation, holding, and selling costs.Financing Blindspots: Even if you’re buying in cash, plan for potential delays or overruns in renovation costs.

Furthermore, since these are turnkey companies and praise themselves on their renovations, the B class turnkey is using only 2% of rent (which averages around $1500/pm) for maintenance, and the C Class turnkey is using 7.5% of rent (avg about $1000/pm) in their calculations.