I'm about to make my first solo DD FOB that will act as a large airpad/storage/minimalist survival essentials (no refineries). I figure I'd share this as a guideline for others.

Adv Fief (40 metal)
Fuel generator x4 (180 metal)
5 storage (225 alu 40 silicon)
Deathstill (60 steel 28 silicon 32 complex machinery)
Medium Cistern (60 steel 30 silicon)
Small Chemical (45 copper)
Pentashield (2 steel 20 cobalt 6 calibrated servok)

1000-1500 granite
500 fuel
260 metal
100 silicon
45 copper
70 steel
40 cobalt
225 aluminum
12 calibrated servok
32 complex machinery
1 corpse

Probably able to carry everything in one assault storage trip then use scout to gather stuff in the Northern PvP region and use assault to haul back to Hagga from the FOB