Previous earnings: no payslips and salary part variable

Hi,

applying for Tier 1 first time. I have two questions.

1. I don't get payslips for my salary. As far as I understand, I'll need to provide tabular data (salary/month) for period claimed. Would this be enough? Would it be possible to provide instead a general letter stating my gross salary/month (for example, we confirm that XXXX receives a gross monthly salary of SSSS)...as it might be difficult to get a tabular salary document from my company

2. I receive 85% of my salary each month and the rest is paid quarterly(3 previous months) - If I provide tabular salary data in my employment letter, it won't look consistent with the monthly package stated on the same letter. Would this be a problem? For example, my letter would say "We confirm that XXXX receives a monthly gross salary of SSSS....and below are salary amounts transferred to his account covering the period from xxxx to xxxx)...The gross salary amount transferred won't match the SSSS amount.

Thank you.