Sure juice from an orange should work, I've done that on a couple occasions. 
Sounds good what you outlined, last thing is make sure they're not any on sort of contraindicated medications, something that might interact, make sure of that and all should be well [though if that dosage were to fully manifest as it has for me and the others I've seen mentioned then that should be pretty powerful].
Set, setting, relaxed, loose, I'm sure you/they know what most of all that is and means, so yeah with all those things in order - all should go accordingly. 
And also, vaping on the comedown is totally fine, though if this experience happens ..as it can [relative to what that dosage is capable of for some people under certain circumstances] ..then it could be potentially sufficient for some time to come. :d
Let us know what happens 
** Also I hope I don't sound verbatim or with certitude, I'm just basing things off of what I've worked with and things I've seen others mention, but we're all different, so yeah .. I'm curious to know how it all goes :d