Its a great idea but you have it installed so low that it will be fked as soon you drive in water. I have a honda pioneer 1000_5. I installed a heater under the seat and 1st summer crossing rivers and sand I ruined the heater. You will have same issues. Now I will install a Diesel heater like that in the box of my Honda which is fully enclosed but a divider between back and front. I will be able to take this out during summer months and install it again in winter. I plan on mounting it to a box that I can remove easily.
Since you have installed this heater in your can am have you had any issues where you are going over bumps and rough terrain to abuse it to not work properly
