Can I report Mortgage Interest for a fully self-contained Motor Home on TurboTax without a 1098? I’ve done it on other online tax platforms for several years?

Yes.  As long as the loan is secured by the motor home and it contains sleeping, kitchen, and toilet facilities, you can deduct the interest as mortgage interest on Schedule A.  To enter in TurboTax Online:

• Select Deductions and credits 
• Next to "Mortgage Interest and Refinancing..." click on Start or the pencil icon
• If you have already entered a Form 1098, click on "Add a new 1098"
• Skip the import by clicking on "Change how I enter my form"
• Select "Type it in myself"
• Enter your lender's name
• Enter the interest and other information for the loan on your motor home.