It is not necessary to cover a board in fondant. It depends on the look you are going for. A board can be covered with foil(comes in many colors)that is made for this purpose. Or any food grade durable paper. HTH
First of all 8", 6", and 4"(assuming the top tier is not for the bride and groom to take home)will not feed 40 people. The usual wedding serving is cut 1" x 2" x 4". The chart that I have gone by for years calculates 36 servings, give or take. It's better to have some leftovers than not enough. So I would def re-think my sizes.
I also don't think you are charging enough for that cake. Especially w/ fondant and all those roses. I would check around with local...
Wow, that's an awful lot to do on the day of the wedding. I would never fill and crumb coat the day of, especially for a wedding. If, for whatever reason, you need to do all the decorating on the day of the wedding, I would fill and crumb coat at least the day before.
You may also want to check out Decorators Cream Cheese Frosting recipe for the outside of the cake.
I make a WASC pina colada cake...I guess you can omit the coconut flavoring if you just want total pineapple.
The pina colada recipe I use.calls for pineapple juice(in place of the water), pina colada yogurt, and pina colada Lorann flavoring. The only bits of pineapple in the cake are from the yogurt, so not a lot. Using pineapple yogurt and pineapple Lorann(in place of pina colada flavors)should do the trick.
There are lots of WASC recipes where liquor can be used or substituted. A good place to start is Macsmom's Gourmet Flavor list. You can also experiment on your own and substitute liquor for some of the liquid called for in the recipe. HTH
I think it would be best to do the marbling just as you would a traditional marble cake(more vanilla than choc).
If you are planning just to add raspberry to your already made vanilla batter, it may be better to use an extract or other raspberry flavoring. My thinking is adding jam to your batter may make it the raspberry portion too heavy
causing uneven baking.
Perhaps making a separate raspberry cake batter to mix in might be better. I have made a raspberry...