Chances are... Joe will be working in one of these three 'professions' for a long time [source]:
Garment Plant - Produces shirts, trousers, coveralls, uniform jackets, U.S. Flags, boxer shorts, sheets and pillowcases, and scrub suits.
Print & Sticker Plant - Produces business and medical forms, brochures, booklets, envelopes, business cards, identification stickers, calendars, PennDot registration stickers, and labels.
Soap & Detergent Plant - Produces bar soap, anti-bacterial soap, liquid and powdered cleaners and detergents, janitorial products, disinfectant cleaners, dilution control systems, and laundry products.
Based upon the inmate hourly wage of $0.19 - $0.42 per hour (though they can get production bonuses of up to $0.70 per hour in addition to the hourly wage)... it looks like it's gonna be a while before Joe pays his remaining debt of $3645.21 in full.