Get the cheapest p-bass that plays in tune and has good action and good frets and fits your hands. Then experiment with strings to get a better sound and feel. Then experiment with pickups and other electronics.
The function of a bridge is to anchor the strings and intonate them. The function of tuners is tune the strings and hold pitch. So don't worry about fancy hardware ideas. Basses are practical instruments. Only change things that don't work for things that do work for specific proven reasons.
It is important to keep your old strings to try out with all the other changes you will make. Bass strings last for years, some would say decades, unlike guitar strings. Don't cut the ends too short, so you can keep reusing the strings.
The function of a bridge is to anchor the strings and intonate them. The function of tuners is tune the strings and hold pitch. So don't worry about fancy hardware ideas. Basses are practical instruments. Only change things that don't work for things that do work for specific proven reasons.
It is important to keep your old strings to try out with all the other changes you will make. Bass strings last for years, some would say decades, unlike guitar strings. Don't cut the ends too short, so you can keep reusing the strings.