What is your husband's interest in 'pre-" home schooling? I have never quite been able to wrap my head around the attraction of preschool for people except that parents like to delegate education from the earliest possible moment, while these same parents choose non-academic preschools because of their superior outcome for children who are not in a disadvantaged home. But what does that have to do with individual parent-directed education?
That being said, you might be able to come to a compromise with your husband by planning out a year that will include developmentally appropriate experiences if you remember that the very best, most expensive preschools in this country also manage to convince parents that they are the height of preschool education while teaching actually not very much.
Appropriate 4 year old activities might include (the list is not exhaustive):
Language arts: Story time at the library, being read to aloud / audiobooks every day, daily exposure to sounds of target second language (e.g., TV, radio, movies, audiobooks, CDs), Starfall.com, Letter Factory / Word Factory videos.
Math / Music: Counting aloud while taking turns (you hold the ice cream cone while I count to 20, then I hold it while you count to 20). Singing: the months of the year, the days of week, etc. little educational memory dittys. Singing and listening to music. Helping measure in the kitchen. Reading the digital clocks.
Movement / socialization: Playground. Bike riding (balance bike first if needed). Swimming. Gymnastics class. Many areas start soccer around age 4.