Absence due to visiting Ireland

Dear All,
I am applying for ILR based on tier 2 (5 years).
During the first three years of living in the UK, I used to visit Ireland regularly and my absence from the country was less than 90 days per year.
My re-entry to UK from Ireland was not recorded on the passport as there is no immigration control for travellers from Ireland. My flight tickets between UK and Ireland were removed from my email so I am not 100% sure of the leaving and returning dates.
My questions are
Do I need to show proof of travelling to Ireland and returning to UK for every visit?
Can I put rough dates for the absence?
Can I attach my payslip for the period of absence to show that I was fully employed?

Many thanks for your help

From the caseworker guidance
https://assets.publishing.service.gov.u ... 2.0ext.pdf

Evidence in the form of a letter from the employer which sets out the reasons for the
absences, including annual leave, must be provided. Where short visits outside the
UK, on weekends or other non-working days have taken place, evidence from the
employer should be provided to confirm the applicant’s normal working pattern and
show the absences occurred during a non-working period.
.
Obtain and upload the required letter from your employer in line with the guidance above which should suffice. In the online application enter approximate dates and explain under Additional Information, or in a separate cover letter, the circumstances and that the dates are approximate .