First Hybrid 08 Prius - ArtCar?! Made for Parades! Need EV switch

I have always loved gas savers but, was afraid of Hybrids due to the history of EV batteries and the expense to replace them. Also I drove an 04 my sister owned and thought it was overly complex. My 76 Corolla E5 got 40 mpg with a 1600cc motor. So, why pay $8000 extra, then to replace the battery 5 years later for $8000? I'm happy to say I'm now a believer.
I found a neglected 08 with 106k mi with bad battery and flat tires that had sat for 6 mos. $1500. I brought my air bottle and watched YouTube videos on how to jump start it. It fired and purred but died when I put it in reverse. This time I drove it out as fast as I could get the cables off and the hood closed. It ran surprisingly well. All it needed was tires, a 12v battery and fluids changed. A trans coolent recall helped.
I build ArtCars and help put on the Tulsa ArtCar weekend. So a transformation is the future for this little beauty. Most parades I do are 2 miles at 1 mile an hour. 5 speeds and cooling issues are a problem, gas mileage is a plus since shows are 500 to 1500 miles away. I was excited to learn of the Coastal EV switch but, when I ordered one they informed me, out of stock and no date of reissue. So, any help would be appreciated. Also any help from nearby Oklahoma Prius tuners would be awesome!
My car is Barcelona red with trim rings removed. So, rather than bore you. I'll share some of my artcars so you can see I'm not only into mpg but smiles per gallon!