It’s pretty much something like this:
McGard 76029 Tailgate Lock, Black https://smile.amazon.com/dp/B0043SCBD4/ref=cm_sw_r_cp_api_glt_fabc_HAM9TGTS5HGNF9D61XA9
I initially had it on mine but decided to remove it because if I really want it I can add it on later with ease. You can also use a hose clap to the same effect.
All Mavericks some with a keyed tailgate to lock it in the closed position. I believe the xlt and above can are powered so you can do it without the key also.
06 mirror swap is exactly what I was gonna say. Super easy and makes a big difference in visibility. Bluetooth head unit is another must-have for me. Would've gone with Android Auto if my 93 had space for a double din.
Get something like this to deter potential tailgate thieves.
Super bright LED reverse bulbs are another swap I do on every vehicle I buy. Previous owner already did it on my truck, it's actually what prompted me to start doing that.
Spray-in bed liner is another recommendation. My truck also has a toolbox which is a must for a single cab but you probably don't need it with the extended cab.
Headache rack for lumber is another big favorite of my truck, but I don't know what you'll be using yours for.
Other than that I also have some LED fog lights and a radar backup sensor. Neither are really necessary but both are nice to have.
McGard 76029 Tailgate Lock, Black https://smile.amazon.com/dp/B0043SCBD4/ref=cm_sw_r_cp_api_glt_fabc_N2RG545EYQ4X33NGYJ97 this is what Ford is selling you for $40
McGard 76029 Premium Pick-up Truck Tailgate Lock , Black https://www.amazon.com/dp/B0043SCBD4/ref=cm_sw_r_apan_i_5N86BF6PBVQ7SS515E1G
McGard 76029 Premium Pick-up Truck Tailgate Lock , Black https://www.amazon.com/dp/B0043SCBD4/ref=cm_sw_r_apan_glt_fabc_G2WSGGBVHC1PVQ5RWEVD
You can get it after the fact. It pretty much something like this: McGard 76029 Tailgate Lock, Black https://smile.amazon.com/dp/B0043SCBD4/ref=cm_sw_r_cp_api_glt_fabc_FAWN6KASZKE6JQTW8NTY
McGard 76029 Tailgate Lock, Black