This is what the Catechism of the Catholic Church has to say about Sunday observance:
2190 The sabbath, which represented the completion of the first creation, has been replaced by Sunday which recalls the new creation inaugurated by the Resurrection of Christ.
2191 The Church celebrates the day of Christ’s Resurrection on the “eighth day,” Sunday, which is rightly called the Lord’s Day (cf. SC 106).
2192 “Sunday . . . is to be observed as the foremost holy day of obligation in the universal Church” (CIC, can. 1246 § 1). “On Sundays and other holy days of obligation the faithful are bound to participate in the Mass” (CIC, can. 1247).
2193 “On Sundays and other holy days of obligation the faithful are bound . . . to abstain from those labors and business concerns which impede the worship to be rendered to God, the joy which is proper to the Lord’s Day, or the proper relaxation of mind and body” (CIC, can. 1247).
2194 The institution of Sunday helps all “to be allowed sufficient rest and leisure to cultivate their familial, cultural, social, and religious lives” (GS 67 § 3).
2195 Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord’s Day
I would think that perhaps you could do the mowing on weekday evenings. You seem awfully concerned with satisfying your neighbors, but I am not there and don’t know your situation. Certainly, there are things we must do sometimes that do require manual labor on Sundays. What the Church is most strict about, of course, is participation in Sunday Mass.
Fr. Vincent Serpa, O.P.