Face it, Altis is HUGE; 10x Stratis. The current Wasteland play mode won't really work if you just scale it up to 10x on everything (spawn points, vehicles, weapons) and keep the same amount of players.
So, do you go with 10x players on a server? My understanding is that Arma III would be unplayable with even 2x players. An alternative is to "go small" on the big map.
Carve the map into "Sectors" and populate only one of the sectors for each mission. Meaning, for an area comparalbe to Stratis, drop in player spawn points, vehicles, crates, etc. and leave the rest of Stratis blank. This would, effectively, restrict player activites to a more playable area, yet leave it open enough to still be a sandbox.
Altis Wasteland: Myrina Sector
Altis Wasteland: Moudros Sector
etc.