The obvious areas like around windows, indication of water around wheel arches inside the MH. The roof area around hatches, antennae or other entries. Look where any trim joins are outside and have a good look inside cupboards etc in those areas. Check any piping coming through the floor. Look for any "cracking" or similar indications on any silicone but this may not mean it's leaking but at least you can look for any water staining in cupboards etc.

Hope that helps.

Give it another go Frangipani. Worked for me on an iPad.

Leaks at the rear ; start with your tailights...