inverter advice

Sounds like we have the same inverter set up , my 400 watt unit had been replaced by a previous owner with a xantrex SW 600. It's been working great for the 5+ years I've used the coach. Looks like the replacement would have taken a half hour at most. It's all the inverted power I need, right now. No charge function required.
If I install a residential fridge , I would up grade.

Magnum or Samlex in that order.

I also recommend Xantrex, they are a reliable brand.

I recommend the GoPower 300 watt sine wave inverter. Very low idle draw and a provision to add a remote switch.

OP didn’t mention microwave. He’s been ok with 400 watts.

wa8yxm wrote:
I will second Ron you might even consider an inverter upgrade to power more you have enough battery to feed up to about a 2000 watt and nuke lunch.

X2, a ProWatt 2000w sine-wave is a good match for most microwaves...

Doesn’t inverter efficiency peak when the unit is operating close to its max? If that’s true, buying a larger inverter than necessary wastes power. See this article and chart:

https://www.solarquotes.com.au/blog/two-reasons-you-must-look-at-efficiency-curves-when-choosing-your-solar-inverter/

I will second Ron you might even consider an inverter upgrade to power more you have enough battery to feed up to about a 2000 watt and nuke lunch.

Xantrex is known for making good inverters. Samlex pro series and Morningstar are good brands too. You want something quiet. The cheap inverters have loud non thermo controlled fans that run constantly.