Auxiliary fuel tank in front of the slide in camper

Yes, that will work well. If you sit it back 18", you could use the lance pods designed for the 815. If you don't use the pods, you will want to make a bracket and mount brake/turn lights. At 10" back the lights will be blocked to at an angle. There is a 4-pin plug wire on each side which the pods plug into so an easy add on without any camper wiring required.