If I can get the annual leave from work I will do PBP 2019.
I will almost certainly stick to the same plan as in 2011 and 2015 which is train from Edinburgh to London and London - Paris with the bike dismantled / packaged to meet the carry on requirement of the Eurostar (85cm so that's saddle, pedals, wheels, handlebars turned and rear mech detached - all protected by some pipe cladding and cable ties to ensure nothing is moving). I bought a camping bag from AMazon which can go over my shoulder nice n easy.
A friend has an apartment between Gare du Nord and Republique where I can assemble bike and leave anything I dont want to take with me on PBP. Train to Rambouillet may be a tad trickier than the RER to St Quentin but no big deal. I can cycle out to the evening start for 90 hr riders if I have to. Being self supported was pretty easy too, all i really needed was spare shorts, a small wash bag, knock rations and a de minimus tool kit.
I did the Baxter Bus from Edinburgh in 2007 and while it was good to have the bus as a bag drop I found the 24hr journey there so hideous that when i got to Brest I booked a flight home at short notice and a friend who was making the baxter bus journey home made sure my bike was on it and I met them in Edinburgh.
Edit - dismantling the bike post PBP is a total ballache I wont pretend otherwise.