You can install a tub in your tiny home but it is not very practical. Walk in showers increase can increase your overall resale cost because they can be used in multiple fashions and target a larger audience.
Here is one of the best how to videos we found on how you can install a walk in shower in your tiny home that is also wheelchair accessible.
Parts for this design are available at most hardware stores or the one from the video is up to 9 square feet shower installation kit from EZable.com. They offer kits from small sized walk in showers for a tinyhouse to giant sized 20 square foot shower.
We recommend installing grab rails on the wall side of the shower for additional support.
Often it is difficult to create a Curbless Shower / Barrier Free shower in an existing home. This innovative system allows users to create a Curbless Shower without modifying the floor joists.
Also see the DIY install a walk in shower using the very inexpensive quick pitch kit. How to install a walk in shower pan in a tinyhouse.