[AngleWyrm]

Found system-level tonnage functions:

Sys_Get_Vehicle_Size_Tonnage_Space: long
plr_index:long
size_id:long

Sys_Get_Component_Tonnage_Space: long
plr_index: long
comp_id: long
comp_enh_id: long

Sys_Get_Vehicle_Design_Remaining_Tonnage_Space: long
design_id: long

//////////////
Looking at the internals of Add_Required_Components_To_Design, the function returns a boolean success, which might be feathered in as a bail flag if a large componant doesn't fit:

replacing:
if (comp_id > 0) then
call Add_Components_To_Vehicle_Design()
set bool_continue_design := TRUE
endif

with:
if (comp_id > 0) then
bool_continue_design := Add_Components_To_Vehicle_Design()
endif