You could ask your realtor about land vs building. Ideally when you set up the rental property you allocated purchase price to both land and building, since land can't be depreciated. You can examine the neighborhood. Have land prices risen disproportionality? The information could also be on the property tax bill.

Not every expense of the sale is included in basis.

Sales Expenses for selling your property include:

• Sales commissions
• Advertising Expenses
• Legal Fees
• Broker Fees
• Transfer taxes

You already determined the structure/land values in the first year you placed those rental properties in service. If you were reporting each property as a physically separate property on your taxes all these years, then you will report the sale of each property independently and one at a time. You can split "EVERYTHING" between the two properties as you see fit, to a point that is believable and reasonable.

Below is guidance for reporting the sale of rental property in TurboTax.

Reporting the Sale of Rental Property

If you qualify for the "lived in 2 of last 5 years" capital gains exclusion, then when prompted you WILL indicate that this sale DOES INCLUDE the sale of your main home. For AD MIL personnel who don't qualify because of PCS orders, select this option anyway, because you "MIGHT" qualify for at last a partial exclusion.

Start working through Rental & Royalty Income (SCH E) "AS IF" you did not sell the property. One of the screens near the start will have a selection on it for "I sold or otherwise disposed of this property in  2020". Select it. After you select the "I sold or otherwise disposed of this property in 2020" you continue working it through "as if" you still own it. When you come to the summary screen you will enter all of your rental income and expenses, even if it's zero. Then you MUST work through the "Sale of Property/Depreciation" section. You must work through each individual asset one at a time to report its disposition (in your case, all your rental assets were sold).

Understand that if more than the property itself is listed in your assets list, then you need to allocate your sales price across all of your assets.  You will only allocate the structure sales price; you will NOT allocate the land sales price, since the land is not a depreciable asset.  Then if you sold this rental at a gain, you must show a gain on all assets, even if that gain is $1 on some assets. Likewise, if you sold at a loss then you must show a loss on all assets, even if that loss is $1 on some assets.

Basically, when working through an asset you select the option for "I stopped using this asset in 2020" and go from there. Note that you MUST do this for EACH AND EVERY asset listed.

When you finish working through everything listed in the assets section, if you ever at any time you owned this rental you claimed vehicle expenses, then you must also work through the vehicle section and show the disposition of the vehicle. Most likely, your vehicle disposition will be "removed for personal use", as I seriously doubt you sold your vehicle as a part of this rental sale.