Recommend not using a remote filter
If you read a few builders sites that have used a remote filter you will see some regret and change to a directly mounted spin-on filter. Problems are weight, leaks and cost. There is not a real good reason for doing it on a RV since a standard spin adapter works well.
Why add the weight, two expensive hoses, and more hose clutter, more possible places for leaks and more holes in the firewall. The remote Airwolf cost $450. I am not sure but I think this is minus hoses and AN fittings which you will need, for an additional cost of another $100-$150. They claim it weighs 4oz but that must not include all the brackets, fittings, hoses and the adapter on the engine. Total weight will be several pounds. For sure it will weigh much more than a standard spin adapter.
The way to go is either the new 90 deg adapter (available on eBay, ECI, ACS) (about $255-$180):
http://www.aircraftspruce.com/catalog/eppages/noslipoilfilter.php
The other option, which it sound like you already have, is the standard spin-on filter, which sticks straight out, about $200-$150 on eBay. This is what I have and works fine. The oil chance problem can be solved with a drain tool.
To ease draining and spilling when changing filter use a drain tool, like this: http://www.aircraftspruce.com/catalog/topages/draintool.php
You don't have to buy the tool and can punch a hole in the can and use a funnel, but the tool is nice, and several are available.
If you are buying from scratch you will need a temp cont'l valve (Vernatherm). You need this with any adapter you buy, remote or not, because none of them come with this valve. New they cost over $200, used you can get them for around $50. There are some with swaged fastener that can come loose, which had an AD issued against them. They work but would avoid those.
So for about $200 scratch you can get a good spin adapter. A remote set up will cost as much as $600-$700 total and weigh more. Don't do it, not needed.
Cheers George