This needs to come from basement & go through the 1st & 2nd floor unit.Install electrical for 3rd laundry setup in basement.Install plumbing for 3rd laundry setup in basement.Patch / fix any disturbance to the 1st & 2nd floor units.Install appropriate amount of windows for legal living space.Install / finish drywall on walls.Install / finish drywall on ceiling.Paint unit.Install flooring.Install kitchen.Install bathroom.Plumbing finish work in bathroom.Plumbing finish work in kitchen.Electrical finish work.No scenario where all of that comes anywhere near $20,000.

I said no, that's an earthworm (I had disturbed it pulling weeds).She said "those things turn into snakes!"

I, -that's me, personally- (not saying you need to agree) find that to be a little disturbing.

Does anyone have any suggestions on how to do this without disturbing the guests on the two different platforms? 

The most disturbing is the absorption rate in my opinion.

Supply chain has already been disturbed.

I've heard various opinions about how difficult it is to schedule both without some degree of conflict and/or confusion and found some very interesting opinions, attitudes and philosophies about this cottage industry that just seems to be getting bigger, better and more successful by the year.I do realize that there are a lot of municipalities and neighborhoods protected by HOA's and CC&R's who are resisting this movement in much the same manner that taxi drivers are resisting UBER and LYFT, however, it doesn't seem to be slowing it down let alone stopping it.I understand and empathize with this dilemma inasmuch as it does pose certain problems and tends to disturb the status-quo of otherwise quiet residential family communities and that has to be addressed and dealt with.However, in destination tourist and vacation communities it's a train that's already left the station and there's no turning back albeit there will be a price to pay in the way of Transient Occupancy Tax (TOT) on the rack rates for this type of rental activity.