Transporting "portable" AC in TM

Our new to us 2006 TM was purchased without roof AC. Since we live in the Northwest where its usually cool and wet it wasn't too bad a deal and the price was right. Now we have a need for AC for a trip to the California desert in the fall.

The price for an AC retrofit is 3,000.00 and has to be done at the factory. Not an option for us.

We got a great deal on a 12,000 BTU portable AC which we now have installed in the TM. It is a dual hose model and vents out of the window just forward of the door in our 2720SD. The unit is around 3 feet high, 18 inches wide, 14 inches deep(hoses make it deeper) and weighs 90 lbs. Yes, it takes up space but it cools well (46 degree output), dehumidifies, is reasonably quiet, has a remote and uses less power than the roof AC. It came with a 2 year in home service warranty and can be returned to any Costco in the US or Canada. All this for 300.00. Depending on the trip we can take it or leave it at home.

Question: How can we secure a heavy item like this for travel? We don't want it to beat the floor to death or the AC. It is too tall to fit in the bathroom and should probably be kept upright for travel. We plan to make a foam base for it to avoid damage to the casters and the floor when traveling and what we need is a way to keep it from bouncing up and down or falling over. Any suggestions?

Thanks, Peter and Martha