So you want to remain tax residence in Bulgaria without staying there 183 days per year?
You probably can't from a strictly legal point of view, but on the other hand, normally no one cares or knows you're tax non-resident unless you tell them.
Confirm with a Bulgarian lawyer, but it's generally quite easy to stay tax resident on paper in a jurisdiction even if you don't live there. Maintain strong ties (rent an apartment, own a house, have some utilities in your name, get private insurances, own a business with some employees, have family there, savings account in BGN with a local bank, and so on) and keep submitting tax returns and paying Bulgarian taxes. If you are a︀ foreigner and need to renew a residence permit, do that as well.
I don't see︁ any real risk that the Bulgarian tax authority would look into you, consider you tax︂ non-resident, and refuse your tax payments.