Weird Japanese bathtub mounting question

I ordered this Japanese bathtub due to the very small bathroom in our early 1900's house. http://tinyurl.com/8mm9e
The tub is *supposed* to be unsecured onto a shower pan. However, due to limitations to the bathroom space we couldn't pour the pan. I built a 4" high motar curb in the corner where the tub will live exactly the size of the feet of the tub and it fits perfectly and installed a slip fit drain. However, this tub only weighs 80 lbs, and due to it being so tall I think there is going to be a problem with people knocking the tub out of alignment and or pulling the drain out of the slip fitting. I don't really want to have to give lessons everytime someone uses the tub.
The tub sits on two 2x4's and I've tried liquidnails, but it doesn't seem to be holding. Could anyone suggest something stronger or something better? Would setting it in a bed of motar hold it?
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
one: brass or stainless steel bracket onto wall stud. two: see grab bar at: http://hdsupply.com/prmw95/mwus/jsp/products/productdetail.jsp?BV_UseBVCookie=yes&_núlse&oid2216&coreSrc=SEARCH&searchText‚0400
Add pictures here
✖
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.