If the batteries are in there ; you don't want to seal it up. They need to vent the gasses created by charging. Covering up the fuses and other items would probably be a good idea , but a lot of those , solenoids and relays produce heat so the area can't be too small.
Here's a picture of the area above my gen set , fuse boxes and relays covered by plexi glass . Plexi removed in the photo , but you can see the rubber seal.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.