There is no difference between a mobile or a brick-and-mortar home. It depends on the area to be covered and the material the home is made of.
In my 70m^2 apartment, made out of brick and plaster, I use two wireless antennae (not mesh, but sharing the same WiFi controller), and that's more than enough; I could probably make do with one if it supported 4 SSIDs.
I don’t know the area it needs to cover, but it sounds like you don’t need a mesh system. Instead, placing your modem/router/AP combo unit in a more central location, and away from the heavy appliances (microwave, oven, fridge) should help a lot.
If you want to use a mesh system wirelessly, you will need a good wireless signal to the “root” device, which involves a good central placement for it.