furnace and water heater lighting issues

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Hi all - I'm having issues with both the furnace and water heater in my 2006 Itasca Sunova that I'm hoping to get some advice on fixing:

Suburban furnace - when turned on it seems to do everything it should, except fire up. The blower comes on for about 30 seconds, then I can smell gas slightly, (outside by furnace exhaust) then fast ticking of igniter for about 10 seconds. This happens for three cycles then shuts down. Sometimes while igniter is going I will hear a short rumble like it almost lights but not quite.

Attwood water heater - This comes on and I can see it light from outside but it won't stay lit for some reason, as if it's not getting enough propane. After a couple tries the red "pilot out" light inside the RV comes on.

The fridge works fine on gas and the stove burners seem to as well. I've tried several times to run stove burners while starting furnace but that hasn't helped yet. I thought I read somewhere that the issue might be the regulator on the propane tank not delivering enough gas or at a high enough pressure to work the furnace and water heater, and since these use more gas than the stove or fridge, they might not work while the others do?

Any thoughts on this or has anyone else had a similar issue? I hate to start pulling things apart if it might be something as simple as changing the regulator.

Thank you!!

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Update: I was just playing with the water heater and got it working by blowing air thru the tube, in case any cob webs or something were in there, and cleaning the contacts on the circuit board. Seems like that is working fine now! The furnace still will not light, and the flames on the stove burners are blue and seem solid, even with the water heater going. Now that water heater going I'm thinking the regulator is OK. As the blower comes on when trying to light furnace, and I hear a click and smell gas when valve opens, then its probably the igniter. I do hear about 10 seconds of clicking, which should be the igniter, but can't tell if it's actually sparking or not without pulling furnace out I think. Seems like if it was sparking it would light.