Honestly you are not in any more risk from this guest than you are from a guest coming from anywhere, including the US. To put things in perspective, Senegal has a infection rate of 955 per million population and 20 deaths per million- Texas has an infection rate of 44,754 per million and 776 deaths per million. You are almost 50 times more likely to be infected by a fellow Texan than a Senegalese.
Anyone can be carrying the virus.
That said, you are not likely to be at risk simply from using the same outside entry gate. You might want to wire a pump container of hand sanitizer on the gate and ask guests to use it before touching the gate (and you use it, too).
As far as the outside sitting area and porch, that is also fairly low risk- it's indoor transmission that is the far greater risk and if there are any shared spaces indoors, you should make them off-limits to guests. However, if possible, I would partition those outside spaces off, with enough space between them, and designate one for the guest and the other for you and your family, so you are not close, and not touching the same chairs or tables. I don't mean you have to put up a wall, but some barrier that indicates which is the guest area. If you and the guest are both using the outdoor areas at the same time, wear masks and keep distance.