building pc for inside a Big truck

[Flashgo1]

What im thinking for the mini power pc i want to put in my big truck. want to upgrade it later when i can bring it home. this is not set in stone. any thing to make it better will help.
https://pcpartpicker.com/user/flashgo1/saved/Z8Jhqs

i would run it off a company maxed allowed 300 watt inverter and it sometimes cuts out on me. wondering if apu would work or there is a better solution out there. using 27 in lcd tv as my monitor that takes 70 watts its self and would like to run it off the apu as well.

Laptops in my price range dont have the power im looking for. hence this monstrocity

 

[Flashgo1]

reason the inverter wave sin is important cause under heavy draw my dc power supply will drop out completely for a few seconds. so i need a UPS to bypass that issue, and some one said the ups needs pure

 

[Karadjgne]

Yes it does. With a DC/DC psu it's important as the Active PFC will drop it like a hot potato at the moment of power interruption. So any UPS will need pure sinewave output, not modified or simulated. Only bad part on those UPS is the price/performance. You can get modified, that'll last an hour at full load for half the price of a active PFC compliant pure wave UPS, that'll last less than 10 minutes. It's why an older, group regulated design would be far preferable in your case as they use Passive PFC not Active PFC. And those older designs are fine with Amd cpus, unlike newer Intel low power states and Haswell compliance.