Haven't seen an Atwood furnace yet that requires removal in order to replace the circuit board. Plenty of people have replaced their furnace circuit board themselves after determining it was faulty by simply following the established troubleshooting procedure.
Dinosaur makes a great replacement circuit board.
There are some furnace installations that do do have the outside access door, just the exhaust vents through the wall - and those WOULD require furnace removal for board replacement.
Ted & Melinda
2016 ACE 27.1
2016 Chevy Sonic Toad