As a senior, Eppler broke the Texas high school record by throwing 71 touchdowns passes in a single season.
After going undrafted in the 2020 NFL draft, Eppler began his professional career in Denmark, taking the Aalborg 89ers to the National Ligaen playoff semifinals in 2021, before signing with the Fundidores de Monterrey in Mexico.
In 2022, he earned the MVP award after leading the league in passing yards and touchdowns, and he became the first foreign quarterback to win a Tazón México.
[4][5] As a junior, Eppler completed 286 of 427 passes for 5,444 yards and 71 touchdowns, leading the Rattlers to a 16–0 record and a Class 4A-I state title.
[7] He also broke the Texas high school record for touchdown passes in a single season, surpassing Travis Quintanilla of Refugio.
[7] Eppler earned first-team MaxPreps Junior All-American honors and was named the Class 4A offensive player of the year by the Texas Sports Writers Association.
[26][27] Eppler got the start in the season opener versus Texas A&M, but Holgorsen played a majority of the snaps in the second half.
[28] The following week, Eppler threw for 263 yards and four touchdowns in a 34–7 home win over Grambling State, combining with Holgorsen for a single-game school-record of 35 completions.
[33] He returned to action on November 3 after missing two games, throwing for 367 yards and tying his school record with six passing touchdown in a 49–47 loss to Abilene Christian.
[34] The following week against McNeese State, Eppler threw for 292 yards and four touchdowns to lead the Demons to a 37–34 double overtime home victory in the rivalry game.
[40] In a season-opening loss to UT Martin, he threw for 387 yards and four touchdowns, breaking the single-game school records in completions (43) and attempts (62).
[45] On October 26, Eppler led Northwestern State to their first victory of the season, throwing a game-winning 1-yard touchdown pass to receiver Quan Shorts in overtime for a 44–41 road win over Incarnate Word.
[50] In the season finale, Eppler threw for 333 yards and two touchdowns in a 32–20 loss to Stephen F. Austin in the Battle for Chief Caddo.
[51] Eppler planned to attend a tryout with the Saskatchewan Roughriders of the Canadian Football League after college, but it was cancelled due to the COVID-19 pandemic.
[54] Eppler debuted in the Fundidores' season opener later that month, throwing a touchdown in a 24–17 overtime loss against rivals Dinos de Saltillo.
[62] On March 25, Eppler threw a pair of touchdown passes to Tavarious Battiste in a 23–20 win over the Raptors de Naucalpan.
[63] On April 3, he threw two touchdowns to newcomer Torin Justice to lead the Fundidores to a 13–10 victory over the Gallos Negros de Querétaro.
[64] Eppler threw four touchdowns, including three to Justice, in the following week's 28–9 victory over the Galgos de Tijuana to secure a playoff berth.
[65][66] Eppler tossed three touchdowns, including two to Justice, in a 35–24 loss to the Reyes de Jalisco to close out the regular season.
[69] In the Tazón México V against the Gallos Negros de Querétaro, Eppler led his team to an 18–14 victory and the first LFA title in franchise history.
On June 14, 2024, Eppler signed with the Vienna Vikings of the European League of Football as a replacement for the injured Ben Holmes.