Of those who like using trenbolone (some simply do not) the very large majority can use 50 mg/day. I would use that rather than 50 mg every other day.
If you insist on making the injections every other day, then 100 mg every other day but this will result in some days being very obviously higher in trenbolone level, and others weak.
Most do not need Arimidex with only 250 mg/week testosterone but there are exceptions.
Personally I would do a blood test before the cycle and include estradiol among the tests. If your value is moderate such as in the 20s pg/mL then I’d doubt that 250 mg/week testosterone would be a problem and personally I’d try without the Arimidex and optionally test estradiol a couple of weeks into the cycle for knowledge. The level would indicate whether it should be added or not.
If estradiol was already in the upper part of the reference range then I’d add it from the start.
Testing can be ordered online rather than needing to seek a doctor’s permission in person.