Just remember the bigger the bed the more of a hassle it is to get level and the stronger the whole printer has to be. If you have any slop anyway it is amplified on a big printer. Even vibration transfers to the print as ripples or waves. My advice is to get a printer that is no bigger than 220mm 220mm bed and one that has auto bed leveling built in and auto nozzle height.
There is software that will slice a print into multiple parts so that you can glue it together later. I wouldnt suggest making but stocks as large parts as the prints normally peel at the layer lines if given enough force. If you print in ABS then you can use accetone vapour to melt the sides and give it a shiny finish. This also makes it a lot more resistant to the layers peeling. Dont think you can spend $200 on a printer and its gonna work straight out of the box. You will be upgrading stepper drivers, fuses, bent rods and warped bed plates for ever. Very frustrating, ask me how I know.
Spend a bit a get a good product and be very careful with the 240v side of wiring. I have swapped over to resin printing now and barely use my fdm printer anymore, 0.2mm layers with fdm compared to 0.025mm layers, heaps quicker, better finish, more detail with resin.
Nylon is a different beast as it requires extra hot temps so u will most likely need an upgraded hot end. Cheap ones say they will do nylon temps and they will for a couple hours but maintaining 240 or 250 deg c for 8 hours plus cost money. Also you will need to store nylon in a very dry chamber. It attracts moisture which then explodes into tiny bubbles as its extruded and creates tiny pores and holes leaving a very rough finish.
Check out Angus at makers muse on youtube. He has a heap of vids to help you make the right choice.