You can get raided by creatures, but if your base occupies most of the terrain I guess only flying creatures will be able to actually raid you. Land enemies can't spawn on water so as long as your island is 40 meters away from the shore you should be good to go.
Land creatures won't spawn inside your base either. To stop raids completely, you could have several islands connected with portals in a way there aren't more than 2 base structures. Example: you can have your bedroom with hearth and bed then go to a portal and move to the workshop island with the workbench and forge, etc. It'd obviously be one hell of a grind but it would stop raids completely.
Or you can make a super fortified tower with all base structures needed somewhere and have your isle of solitude for rest and cosmetic building.