In my opinion , Unless the dealer has s coach already ordered , about to go to production and can modify it to meet your order , No.
most RV manufactures are making the last of he 18’s now and preparing to switch to the 19s and many shut down to do this.
Yes never go with just one bid esp if your using camping world. In any case you should get 4 -5 bids on any “new” order that will take a week minimum .. your timeline ( for a new order) doesn’t seem reasonable ... finding one on the lot that fits your specs .. maybe.