You are able to build and play a base as described, but something to note is that locking down jump connections to hostile IDs by using player base weapons platforms is seen as bad form these days, and likely to see a base doing it destroyed quickly. In addition, depending on where you want to build, some roleplay restrictions (separate from server rules) may apply and you may need to contact local authorities to ensure compliance with their laws and avoid them coming knocking with battleships. You can find all laws that apply in the game world here: https://discoverygc.com/forums/showthread.php?tid=8584
I cannot see a reason to put up one where there is a border station already but NL- Cambridge would be an example of a suitable place. Same as in Liberty Cali - Cortez. Would it, being a lawful government operation, attract fees? I don't intend these to be anything other than core one as its sole role is policing.
I see that in Liberty... "All new modular stations must have minimum distance of 10 clicks from nearest planet, station, Jump Gate, Trade Lane, etc." So would that preclude a Liberty law enforcement police border station at a JG?
In Bretonia it has the same. "Bases must be no closer than 10K from any existing Base or Jump Gate, unless Special Permission is granted." There is a possibility to get special permission.
Gallia does not specifically have a restriction from JG's etc.
Rheinand has 10k from anything but exemptions can be possible. "§7.2. All modular bases have to be built at a distance of at least 10K from existing installations and other solar. §7.2.1. Exemptions to §7.2 can be made if there is a compelling or historical reason to do so. Exemptions will require thorough documentation."
We will welcome any such attempt at RPing a base and fees will be waived as well as licenses should it be stated by BPA inRP that there will be a border station set up.