In light of the 1962 regulations for Lenten Penance I suggest the following Lenten Fast for traditional Catholics.
This is the Lenten fast "strongly recommended" by the Bishops of the US, "On Penance and Abstinence", 18 November 1966, paragraph 14.
These rules would apply to all days except Sundays and exempt Solemnities, which are not days of Penance.
Fasting* every day from Ash Wednesday until midnight of Holy Saturday: one full meal a day with two smaller meals that do not equal the main meal, and no snacks between meals (except water+), with abstinence as follows:
Total Abstinence**.
Wednesdays+
Fridays
Saturdays
Partial Abstinence: meat permitted at the principle meal only.
Mondays
Tuesdays
Thursdays
*Strict fast on Ash Wednesday and all Fridays: no food or drink, except to take a quick and light snack (e.g. bread and water) at the end of the day, if needed.+
**Abstinence forbids the eating of flesh meat and of broth made from meat, but does not exclude fish, eggs, dairy products or seasonings made from the fat of animals.
+ Indicates a norm adjusted by Plinthos.
P.S. This fast (which typically permits one decent meal each day) is demanding but not hard to do and very rewarding spiritually. It is what believers have done from the beginning of time!
Cf. Newark traditional lenten fast regulations, 1873.