Combine the two into one and then add two more that will allow its use indoors and underground. Tag a 1p cost to it too.

WEAVE DISGUISE (or something)

When used indoors, the extra line added to the room desc will resemble... a piece of furniture. When in natural outdoors, it'll be a rock, boulder, log, bush, etc. When underwater, a thermal vent, seaweed, etc. Underground: boulder, stalactite, stalagmite, crevice, etc. Roads: signpost, statue, etc.

This is primarily for fluff purposes, as it really doesn't matter what shows since that extra line is the give-away of someone's presence. And the power cost is there as a trade for allowing its use in indoor/underground locations.