What boat ?? (brand/model/length or pics would help)
Several members have "transport racks" of various designs that are specifically made to transport multiple long rods (on road or water). You will likely have several members offer their opinions on which is best, so the choice is yours.
I can't offer any recommendations as I don't "Spider Rig" per se ... I mostly "Push" jigs/cranks with my long rods .... and I currently only have three 14' rods. They and all the other one and two piece rods are covered with various brands of rod socks & transported in the rod locker of my boat. When in use they are strapped down on top of the rod locker when moving from place to place. My fishing partner's rods are dealt with the same, rod socks or not. (My boat is a 16' ProCraft 1999 model) It doesn't take me but a few minutes (on the water) to put the long rods together and in the rod holders ... but, if I had 8 of them, I would put them together prior to launching and strap them down on the rod locker.
I have a seaark side console RXT 872.....18 footer