Much simpler to just find an old DN receiver (doesn't need to have card or be subscribed)...and if you are not using a 2nd dish then ya don't need anything else for power..
The cheapest is an old Dish receiver kept on all the time on one output of a DP34 switch. If it is not easy to find a power inverter, you can use a DP44 switch which is usually sold with a power inverter