with the way oda is hyping up the scared man it is obvious that fluffy and co would meet him. also there won't be much stake since the strawhats can copy there own poneglyphs so them losing it in the davy back won't create any tension.
Of course they can, but they would still need that last RP and even if they have 17 copies of the other 3, it won't help their cause. So it's not about the risk of losing the 3 they already have, but rather about winning the last one.
So if Buggy gets it first, they would have a problem. Obviously certain things have to allign in order for it to happen, but it's possible.
And I personally think it's the best way to make CG competitive instead of magically boosting them up to Yonkou crew manpower. The BPs, the RHs and the SHs are all very powerful. It's not as easy as many people make it out to be.
Especially when Mihawk is their strongest fighter, that would already get taken care of by Zoro, who's just the No2. Good luck finding a random, who can fight near EoS Joyboy 2.0.
This way they could get into the race by just obtaining the last RP, all within a relatively short amount of time (which is a must in the final saga) and they do not even have to have Yonkou Crew strength for all that to happen.