There are only 4 mod menu's confirmed to be working that have multiplayer options:
Outdated working mod menu's:
Kr0wns V1.5
Washed Out V2.1
All free versions of Endeavour
Updated working Mod menu's with all the stuff from 1.28 added:
N Mod Menu v4.20 and the paid version
Kinky 2.2 (Has no multiplayer options)
Simple trainer (Has no multiplayer options)
Mehyoo (has multiplayer options but all of them are disabled for now)
All mentioned menu's, except the endeavour and N menu's can be found on the forum.
Use one of the mentioned menu's with the latest scripthookV and dinput8.dll.
*Currently the Car spawners do not work on most menu's, up to this point, i think N menu has a somewhat working one though.