1966 Safari 22' Water Heater

[Breon]

Looking for help with water heater replacement options on my 66 Safari that do not require exterior mods. Newer units seem to require smaller exit hole than original and I would like to avoide mods to skin.

Also, are there drop in, new toilet options and if not, where can I get a "rebuild" kit? Window and door seals are all shot. Need those too. I'm new to this world of Airstream restoration so don't assume I know anything; I don't.

Thanks,
B.