Took Millicent on her first trip of the year, Memorial Weekend. About 800 miles.
After sitting since November, she fired up instantly. I credit this to new fuel hoses (which do not leak air into them while sitting with zero fuel pressure), the new starter (which cranks good-n-fast), and the three batteries -- new three years ago -- to power that starter with gusto. Good starter and batteries cost money, but without them a bus is nothing but an improvised chicken coop. I charge the batteries occationally during the winter to keep them healthy.
Storage of luggage and supplies remains a problem. We installed some shelves last year, but we need much more. I'm visualizing something like the suitcase rack in airport shuttle buses.
We hardly ever have two people sitting side-by-side on the dinette benches. But we often have two people struggling to squeeze past each other in the isle. You might want to consider this when designing your interior.
Similar problem with upper bunks. I'm planning to narrow them a couple of inches, but also installing very strong safety fences. I cannot sleep in a bunk if I fear falling out of it.
Shower water: Still no water heater in Millicent, but I did take a shower. So long as I was receiving the water that had been standing in the pipes inside the bus body, it was mild enough. But when water arrived from the 55 gallon barrel, it was awful cold. I conclude that hardy people may be able to skip the heater and simply run a couple of gallons worth of pipes in the interior of the bus, picking up "room temperature" -- assuming adequate room temperature, of course.
About that under-seat heater where I had a fitting blow off last year: First of all, no plastic fittings! But now I solved the whole problem of the 90 degree bend in the hoses -- by turning the heater 90 degrees instead. (The factory uses plastic guides that keep the hoses from kinking, but I thoughtlessly discarded those long ago.)
Now the hoses come over the front wheel-well and straight into the heater core pipes. The unit seems to work perfectly fine on its side. Just don't block the air flow with luggage or anything.
There ought to be vents at the highest points of the hoses so the system can be filled properly -- unless you have a heater circulation pump, which some Blue Birds have.
And we need a shut-off valve inside the bus, for travel in warm weather. The factory installed one on the instrument panel of course, but the lever and cable stuck ages ago. Repair indicated!
The fuel filler hole finally annoyed me enough, so I took power tools to it. The job is not finished, but you get the idea:
The fuel gauge quit working. This apparently happened in conjunction with running out of fuel on a long steep hill last November. Surgery is indicated.