If you don't want to use the toggle or query each time, making your own saving throw macros will be easiest.
Make a character called Macros (if you don't already have a macro character sheet).
Pinch the default NPC saving throw macro.
Paste it into an Ability macro on the Macros sheet using the same naming as default: npc_save_wis for example
Either hardcode it with /w gm at the start of each saving throw macro, or use the wtype saved on the Macros character sheet as your toggle if you think you might want to change it later:
/w gm &{template:npc} @{selected|npc_name_flag} {{rname=^{wisdom-save}}} {{mod=[[[[@{selected|npc_wis_save}]][WIS SAVE]]]}} {{r1=[[@{selected|d20}+[[@{selected|npc_wis_save}]][WIS SAVE]]]}} @{selected|rtype}+[[@{selected|npc_wis_save}]][WIS SAVE]]]}} {{type=Save}}
or
@{Macros|wtype} &{template:npc} @{selected|npc_name_flag} {{rname=^{wisdom-save}}} {{mod=[[[[@{selected|npc_wis_save}]][WIS SAVE]]]}} {{r1=[[@{selected|d20}+[[@{selected|npc_wis_save}]][WIS SAVE]]]}} @{selected|rtype}+[[@{selected|npc_wis_save}]][WIS SAVE]]]}} {{type=Save}}
Once you have the six saving throws all saved under Abilities, change your menu macro above to call those instead of the @{selected} version:
{{description=[STR](~Macros|npc_str_save)[DEX](~Macros|npc_dex_save) .... and so forth
The new versions still rely on having the correct token selected when clicked to grab their saving throw bonus, but no longer rely on the npc sheet's wtype setting.
Obviously this will only affect saving throws - if you need secret rolls for stealth, perception or anything else that will be another couple of macros to customise.
I know your subject says "without additional macros", but this will take 5 minutes to set up and is universal. The only other way to achieve it is setting whisper type to Query, as Mark said.