Follow up: here's how to quickly set a myname.internal domain name. Use ssh to copy & paste in the commands. Be sure to change DOMAIN to taste and match ROUTER_IP to your device's IP:
DOMAIN='mycustomnamehere'
ROUTER_IP='192.168.8.1'
uci batch <<- __EOF
set dhcp.@dnsmasq[0].local='/internal/'
set dhcp.@dnsmasq[0].domain="${DOMAIN}.internal"
set dhcp.@dnsmasq[0].expandhosts='1'
add dhcp domain
set dhcp.@domain[-1].name='router'
set dhcp.@domain[-1].ip="${ROUTER_IP}"
__EOF
uci commit dhcp && service dnsmasq restart