In fact, if you really want to go lazy, you should just construction-adhesive an insert over the tile.

This is the method I've used for looking at duplexes / triplexes to live in and manage.You can model your primary residence in the same way as any other income asset with the crucial exception that you insert some math for how things work out when you pay rent to yourself. 

The joists are then hung from this perimeter by inserting them perpendicular between the outside perimeter and the field laminated 4x12 ((2, 2x12s lag bolted together)intermediary cross beams that are pinned to #4 rebar that I cast into smaller, interior support piers.

I am a cheap SOB , so I will be loading it in the pickup with the dump insert , and a trailer , I can make 4 tons in 1 trip .

May want to do the white inserts though. to add some privacy for the back yard.

Assuming she meets all your requirements (insert Alex's and other posts here)--you seem concerned about the income to rent ratios. 

Inserting new walk in shower, toilet and vanityHall bath.

You have one side of story. landlord however will be less likely to lie to fellow landlord and I weigh landlord references over all credit reports, and tenant provided information etc. perfect credit doesn't really matter if the last landlord told me the applicant was a nitpicker, always late with rent, dirty, or [insert nightmare issue here].please be sure to reference the screening primer to make sure you have all other aspects covered:http://www.biggerpockets.com/renewsblog/2011/3/31/screening-tenants-primer/

Recently on 2 SFH rentals we had to seal our WBFP's then have them re-inspect it to avoid losing our Insurance.On a higher end SFH I took out the old WBFP & installed a Gas insert with blower & they love it.We did have an issue in an old rental home years ago where the fire was so hot the support joists under the hearth actually started to smolder.

Usually when fiberglass tubs and inserts are installed the installer puts down a bed of fix-all or mortar and then “squishes†the tub into the bed for support.